Unit 4 Amazing Science 课时课堂练习 2022-2023学年仁爱版英语九年级上册（含答案）

仁爱版九年级（上）英语Unit 4：《Amazing science》课堂练习
Unit 4 Topic 1
Section A
I. 用方框内所给的词的适当形式填空。
be made of be made from be made in be made by be made into
1. This watch __________________ China.
2. The paper ___________________ wood.
3. The cake ____________________ my sister.
4. The scarf ____________________ silk.
5. The wine ___________________grapes .
be used for be used as be used by
6. English _________ widely _________ many people from different countries.
7. Knives __________ cutting things.
8. Mobile phones ____________ tools that make people communicate easily.
II. 句子翻译：根据汉语意思完成句子。
1.我妈妈允许我做完作业后看电视。
My mother allows me_________ ____________TV after finishing my homework.
2.这个MP3是用来听英语歌的。
The MP3 is used for ____________ _______ English songs.
3.我们的书桌是木头制成的。
Our desks ______ _____________ ______ wood.
4.可以把你的新手表给我看看吗？
Can you ____________ your new watch______ me
5.我从我的老师那学到很多关于宇宙飞船的知识。
I_________ ________ _________ _______ about spaceship ________ my teacher.
Unit 4 Topic 1
Section B
I. 根据句意，用括号内所给的提示完成句子。
1. Do you know who_________ (发明) the airplane
2. Edison made more than two thousand _________ (invent) during his life.
3.A speech on How to Learn English Well ________ ________ (give) on the
playground last night.
4. The first jeans _____ __________ (produce) in 1855 in America.
5. _________ _________ _________ (据说)four people were killed in that accident.
II. 句子翻译：根据汉语意思完成句子。
1. 据说他一生发明了两千多样东西。
It’s said that he invented more than two thousands things _____ _______ _______.
2. 这架老飞机和今天的飞机不一样。
The old airplane _________ _____________ ___________ today’s.
3. 这些帐篷由这种布制成。
The tents __________ ___________ _________ this kind of cloth.
4. 竹子可以被制成纸张。
Bamboos can __________ ___________ ___________ paper.
5. 试试这件衬衫，你会感觉舒服些。
Try on this coat and you’ll _________ __________ ______________.
III.句型转换。
1. Mr Green watered the flowers yesterday.(改为被动语态)
The flowers _________ _________ by Mr Green yesterday.
2.The laptop was developed in Japan in 1985. (划线部分提问)
_________ and _________ was the laptop developed
3.The light bulb was invented by Thomas Edison. (划线部分提问)
_________ _________ the light bulb
Unit 4 Topic 1
Section C
I. 根据所给提示填空，每空填一词。
1. We all agree that computers are the most useful i___________.
2. Peter is a clever boy, but he made a lot of s_________ mistakes in the test.
3.What shall we do tomorrow Do you have a ___________/ θ :t/
4. —What’s the ___________/'r ub t/ made of
— Metal. It can walk, dance and talk like humans but it can’t think like us.
5. They could fly over high mountains with the help of _______(热气球) at that time.
6. Do you know the meaning of the symbols on the ___________(键盘)
7. They are playing games with toy _________ (枪).
II.看图写话。
1. make, silk 2. invent，1876 3. use 4. build，next year
1._____________________________________________________________________
2._____________________________________________________________________
3._____________________________________________________________________
4._____________________________________________________________________
选做题
Do you want to be an inventor Do you want to invent something Write a passage about your invention. The following questions may help you.
1. How do you come to the idea of your invention
2. What does it look like
3. What is it made of/from
4. What’s it used for
5. What are you going to name it
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Unit 4 Topic 1
Section D
I.情景交际。
1 .你想告诉你的朋友收音机是1895年发明的，可以这样说：
_______________________________________________________________
2. 你想知道汽车是谁发明的，可以这样问：
_______________________________________________________________
3. 你想告诉他人灯泡是爱迪生发明的，可以这样说：
_______________________________________________________________
4. 你想祝福对方梦想成真，可以这样说：
_______________________________________________________________
5. 你想向他人询问计算机是被用来做什么的，可以这样问：
_______________________________________________________________
II. 短文填空(共10小题)
阅读下面短文，根据语境、音标或所给单词的提示，在每个空格内填入一个恰当的词,要求所填的词意义准确、形式正确，使短文意思完整、行文连贯。
It is reported that some developed countries have shipped broken parts of computers to China. Such a thing can be founded every day __1__ it is against international laws. Last month Hong Kong officers found 131,000 kilograms of broken computers, TVs and phones send from Japan.
Things like these are called electronic waste, or e-waste. Many ___2___(place) in China are polluted by e-waste. Guiyu in Guangdong province is one of them. This town is named as “the e-waste ____3____/'k p tl/ of the world”. It has to deal with 1.5 million kilograms of e-waste each year, from which it makes 75 million years. But it comes at a cost. Many of the poison in e-waste find their way into the _____4____. Plastic is burned __5____(outdoor) and chemical water is poured into rivers. Greenpeace, an environmental group, has found the air, the earth and the water in Guiyu badly polluted.
The Chinese government wants the country to ____6____ /d 'vel p/, but in a way that doesn’t do 7 to the environment and people’s life. This year, China presents a new protection law, the strictest one we have 8 puter companies like Lenovo and Dell will be 9 /r 'kwai (r)d/ to recycle their old computers. This is because the producers that make computers know best to deal with them safely. Hopefully, the problem with e-waste will be _ 10_ (solve) in near future.
1.__________ 2.__________ 3.__________ 4.__________ 5.__________
6.__________ 7. _________ 8.__________ 9.__________ 10.__________
III. 短文写作。
手机给人们的日常生活提供了许多方便，但是使用手机也存在着一些弊端。作为一名中学生，你对学生持有手机有何看法？请你结合以下图示写一篇80字左右的短文。
注意事项：
必须包含所有提示信息，可适当发挥，开头已给出，不计入总词数；
意思清楚，表达通顺，行文连贯，书写规范；
请勿在文中用真实的姓名和校名。
More and more people have mobile phones in China.____________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Unit 4 Topic 2
Section A
I. 根据所给提示填空，每空填一词。
1. I seldom eat junk food _________ ________ ________ keep healthy. (为了)
2. Can you tell me which river is the longest river_____ ______ ______(在地球上)
3.There will be a wonderful movie this evening. I’m excited and _______ ______ _____ watch it. (迫不及待地)
4.I believe that our dream ________ _________ _________ one day. (将会实现)
5. He _________ playing the guitar _________ playing the piano. (和…比，更喜欢)
II. 根据要求完成句子。
1. Many people discussed aliens those days. (改为被动语态)
Aliens ____________ __________ by many people those days.
2.Robots will drive the buses and taxis in 2048. （改为被动语态）
The buses and taxis_________ ________ _________ by robots in 2048.
3.We will plant trees and flowers under the sea in the future. (改为被动语态)
Trees and flowers _________ ________ _________ under the sea in the future.
4.I get up early so that I can catch the early bus. (改为同义句)
I get up early ________ ________ _______ catch the early bus.
5. He believes that his dream will be realized. (改为同义句)
He believes that his dream __________ _________ _________.
选做题
III.短文填空
What is calligraphy It's handwriting. Any language can be written in calligraphy, but Chinese calligraphy is especially beautiful. It takes a lot of (1)______(patient) and practice to write Chinese calligraphy. People take lessons to learn how to do it.
2_________ [ dj r ] the lessons, they learn how to hold a brush. 3______ also learn how to make different strokes(一笔）to make Chinese characters.
There are many different kinds of brushes people can buy to do calligraphy. Different 4_________(brush) are made from different animals' hair. But there is one kind of calligraphy brush that is really 5________ [ spe l]. This brush is made from baby hair! Hundreds of years ago in China, people started to 6 _________ [b li v] a baby-hair brush was good luck. It is a 7______(traditional) but no one is really sure where it comes from.
Today people in Asia still have brushes made from baby hair. To make a brush, parents will cut off a baby's hair 8 _____he or she is about one month old. Then they will take some of the baby's hair to a shop to be made into a brush. 9______(make) a brush is not easy. It takes more than 80 steps to make one brush. That's why these brushes are such10_________ treasure.
Unit 4 Topic 2
Section B
I. 词汇运用：
选做题
用cover/discover/ discovery/ discoverer/的适当形式填空。
The fact is that he did not _____________ it.
New scientific ____________ are being made every day.
The planet was named after its ______________.
The ground is______________ with snow.
用discover/invent/find/find out 的适当形式填空。
Columbus ___________ America in 1492.
The inventor ___________ a lot of inventions all his life.
Have you ___________ why he was late
Tim looked for his pen everywhere. Finally, he ________ it under the bed.
II.根据句意，用括号内所给的提示完成句子。
The cake __________ _________ _________(完成) very soon.
Our cars __________ _________ _________ (生产) by robots in the future.
The article says the houses __________ _________ _________ (建造)under the sea in the near future.
Some basic computer skills __________ _________ _________(应该掌握) by us.
III．情景交际。
1.你问你的朋友是否听说过超人的故事，可以这样问：
Have ______________________________ superman
2.你想说它真的很酷，可以这样说：
____________________________________________
3.你告诉朋长大后想成为一名科学家，可以这样说：
____________________________________________
4. 你想知道火星长什么样，可以这样问：
____________________________________________
5. 你想告诉同学今晚将有一场精彩的电影上映，可以这样说：
____________________________________________
Unit 4 Topic 2
Section C
I. 根据句意，用括号内所给的提示完成句子。
He __________ _________ _________ (以命名)his father.
My brother ___________ (重)30 kilos. He is a little thin.
This summer holiday I had a good ____________(旅行)to the Mount Huang.
If you want to get more ___________(信息)about the space, please search the Internet.
The police followed the man __________ _________ _________ _________ (相隔)about 50 meters.
It ___________ _________ _________ __________ since we landed on Mars.
= It __________ _________ _________ since we landed on Mars. (两天)
The _________(暴风雨) blew down many trees last night.
II.根据语境、音标或所给的词完成下列句子。
1. The __________[st (r)m] was so strong that it blew down many trees last night.
2. Tom’s __________ is 90 kilos. He is too heavy.
3. —I’m flying to New York to visit my uncle next Monday.
—Have a good ____________[ d (r)ni].
4. They are looking at the computer ___________. [skri n]
5. I believe my dream will be ___________ (realize) one day.
6. Yang Liping likes dancing a lot. She is an excellent ____________(dance).
7. The man is ____________(describe) his beautiful hometown.
选做题
8. Yang Liwei is an ____________. He is the first Chinese to travel into space.
III. 综合填空。
Copernicus was an astronomer(天文学家). He studied the 1 (planets/weather) and the stars. He found out that the earth 2 (walks/goes) around the sun. He put his thought into a book, but he hid the book. Nobody could read it 3 (before/after) Copernicus died.
Many years later, Galileo 4 (read/watched) the book and believed that thought. Galileo said that the earth was moving around the sun. This made lots of people 5 (happy/angry) because they thought the earth must be the center of the universe. Galileo got into trouble and he had to say that he was 6 (brave/wrong), but Galileo knew he was right.
Galileo watched the moon carefully through his telescope(望远镜). He 7 (invented/saw) some hills there. He also saw 8 (millions/millions of) stars in the universe. In 1673 his eyes became weak, and then he couldn’t see 9 (anything/nothing) through his telescope.
Galileo died in 1642 and the world lost a 10 (funny/great) man. But in the same year, another great scientist Newton was born in England.
1.____________2.____________3.____________4.____________5.____________
6.____________7.____________8.____________9.____________10. ____________
Unit 4 Topic 2
Section D
I.词组翻译。
1.迫不及待做某事_______________ 2.钦佩某人_______________
3.发现新事物___________________ 4.掌握电脑技能_________________
5.表演芭蕾_____________________ 6.在舞台上_____________________
7.离......有多远__________________ 8.以……命名___________________
9.限制……的使用_______________ 10.在地球上____________________
II. 单项选择。
( )1.—You will be famous _____ if you keep on working hard.
— Thank you.
A. some days B. the day C. one day
( )2. —Most housework ______ by the robots in the future.
—I agree.
A. will do B. will be done C. is done
( )3.The population in the USA is about _____ it is in China.
A. one-fourth B. one-fourth as large as C. one-fourth large
( )4. —How many books did you borrow in the library
—Three. I borrowed one yesterday and ____ two this morning.
A. other B. the others C. another
( )5. —Did you see the accident happen with your own eyes
—Yes. And the police asked me to ____________it.
A. tell B. describe C. show
( )6. —This problem is ______ me. I’m afraid I can’t work it out.
—Don’t worry. We will help you.
A. beyond B. beside C. behind
选做题
III.短文写作。
2013年6月，中国成功发射神州十号宇宙飞船，并实现与天宫二号顺利对接，看到这消息，我很激动。请根据以下4个问题以 I want to be an astronaut为题写一篇80个字左右的短文。
What do you think of the astronauts
Are you interested in science
What do you want to be
What will you do to achiever your dream
In June, 2013, the spaceship Shenzhou X was successful sent into space. I was_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Unit 4 Topic 3
Section A
I.用that, which和who填空。
1.That boy ________ has a big nose is my good friend Tom.
2.The bike________ I bought yesterday cost me 280 yuan.
3.These classrooms___________ were built last year are very beautiful.
4.Wang Yaping is the first woman astronaut___________ gave us a lesson in Shenzhou X spaceship.
5.China is the third nation _________ sent a person into space.
II. 词汇运用：用单词的正确形式填空。
1. Yang Liwei is our ___________(nation) hero.
2.What’s more, we have launched _________( other) four spaceships in the past few years.
3.They spent 2.5 hours __________( explore) the moon.
4. The spaceship returned to the earth __________(safe).
5.It __________( prove) that China has made great progress in its space industry.
6.All of us are very_________ (pride) of our country.
III.情景交际。
1.你想对朋友说那儿的人可真多啊，可以这样表达：
_____________________________________________
2.你想知道谁是第一个进入太空的中国人，可以这样问：
_____________________________________________
3.你想表达你们所有人一定都很自豪，可以这样说：
_____________________________________________
Unit 4 Topic 3
Section B
I.汉译英。
1. 下决心做某事___________________ 2. 建议某人做某事_______________
3. 控制宇宙飞船方向________________4. 掌握计算机技术 _________________
5. 发现一些新的办法________________6.更好为我们服务 _________________
7. 改变速度_________________ 8. 也…一样___________________
II .情景交际。（根据对话的内容，把空缺的句子补充完整。）
你想问宇宙飞船是用来干什么的，你可以这样表达：
_______________________________
你想告诉你弟弟，宇宙飞船是由计算机控制的，你可以这样表达：
_______________________________
你想问计算机是怎么工作的，你可以这样表达：
_______________________________
III．单项选择题。
（ ）1.I’ll never forget the story_______.
A. that cheers me up B. who cheers me up C. what cheers me up
（ ）2. Kangkang _______go to bed late. But now he is used to going to bed early.
A. was used to B. is used to C. used to
（ ）3. Thanks _______ your introduction, I’ll work hard to achieve my dream.
A. for B. to C. at
Unit 4 Topic 3
Section C
I.根据句意，用括号内所给的提示完成句子。
1._________ __________ __________ （毫无疑问）that you are right.
2. In business, computers are used to _______ and ______ ______(预定和取消订单).
3.In factories, robots are controlled by computers that are like human _______[bre n].
4.The two cities _________ _______ ________ (被…连接) a bridge.
5.The ring looks _______ ['ta n ]but quite expensive.
6.The outside of an orange is a little bitter, but the i________ is sweet.
7.Computers help us at work and at home, but they must be used ________(恰当地).
II.单项选择题。
( )1.Everyone is all here_______Lilei, because he is ill in hospital.
A.besides B.except C.as well as
( )2.Robots can do dangerous things_______ human being.
A.instead B.instead of C.among
( )3.In order to keep healthy, he keeps _______every morning.
A. exercise B. exercising C. exercised
( )4.Two thirds of this work has been done. There is _______to finish the task in two days.
A.no need B.no doubt C.no way
III．选做题
最近，用手机APP买菜的人多了。手机菜场菜品丰富、洗净配好、预约送菜上门……外国朋友对此也很感兴趣。假如你是李华，请你以A New Use of the Mobile Phone 为题，写一篇短文，向外国朋友介绍用手机买菜带来的便利，让外国朋友了解中国人民生活中的这个新变化。次数80左右。
Name A New Use of the Mobile Phone
Contents Everything you need for a meal
Benefits 1. save time and energy 2. enjoy a more relaxing life
注意事项：
1. 必须包含所提示的信息，可适当发挥；
2. 意思清楚，表达通顺，行文连贯，书写规范；
3. 请勿在文中使用真实的姓名、校名及提示信息以为的地名。
A New Use of the Mobile Phone
_______________________________________________________________________________________________________________________________________________________________________________________________________________
_______________________________________________________________________________________________________________________________________________________________________________________________________________
Unit 4 Topic 3
Section D
I. 根据语境、音标或所给提示词完成下列句子。
1. It’s ________ [ s (r)tn] that we will succeed.
2. The teacher often ___________(warn) the students not to go there at night.
3. Germs are so _________ that we can only see them by microscope.
4. Mary often helps her mother do some ___________ [ ha sw (r)k]on weekends.
5. There was a __________ [ m ɡ zi n]on the table.
6. My parents watched CCTV news after supper as __________ last night.
7. Now many families own their _________ (person) computers in China.
8. The basketball match was __________ (cancel) because of the storm yesterday.
9. The Hong Kong-Zhuhai-Macao Bridge __________ (connect) the mainland to Hong Kong and Macao.
10. The _______(wife) were waiting for their husbands at this time yesterday.
II.根据要求完成句子。
1.That man is talking to Jim. That man is Mr. Smith.（并成含定语从句的复合句）
That man ________ _________ ________ __________ __________is Mr. Smith.
2.I borrowed a book from the library. The book was written by Bing Xin. （并成含定语从句的复合句）
The book ________ _______ _______ from the library ______ _____ by Bing Xin.
3.It’s true that we have made great progress in space industry. (改为同义句)
There is _______ _________ that we have made great progress in space industry.
4.The boy can’t work out the problem by himself. (改为同义句)
The boy can’t work out the problem _________ _________ ________.
5.The mother ________ the boy ________ ________ play the ball in the street. (警告…不要做…)
6.No one knows where he has gone ________ ________(确切地)
III.短文写作
下面是某班学生做了一个调查报告的结果，内容是“关于上网的利弊”，请你根据结果介绍他们的观点，并给出你的看法。
赞同（60%） 反对（40%）
1.可以从网上获取所需的信息 1.上网浪费时间和金钱
2.对学习有帮助 2.网上有学生不宜阅读的东西，对其有害
3.在网上交朋友 3.网上交的朋友不可靠
4.通过网络交流快捷方便 4.和朋友联系可以写信或打电话
你的看法
The table tells us that 60% of the students think getting online is very helpful._______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
参考答案：
Unit 4 Topic 1
Section A
I.1. is made in 2. is made of 3. was made by 4. is made of 5. is made from
6. is used by 7. are used for 8. are used as
II. 1. to watch 2.listening to 3. are made of
4. show to 5. have learned a lot; from
Unit 4 Topic 1
Section B
I.1.invented 2.inventions 3. was given 4. were produced 5. It’s said that
II. 1. during his life 2. is different from 3. are made of
4. be made into 5. feel more comfortable
III.1.were watered 2.When, where 3.Who invented
Unit 4 Topic 1
Section C
I. 1.inventions 2. silly 3. thought 4. robot 5. balloon
6. keyboard 7. guns
II. 1. The T-shirt is made of silk.
2. The telephone was invented in 1876.
3. The camera is used for taking pictures./ to take pictures.
4. The hospital will be built next year.
III.选做题（略）
Unit 4 Topic 1
Section D
I. 1. The radio was invented in 1895.
2. Who invented the car
3. The light bulb is/was invented by Thomas Edison.
4. I hope your dream will come true./ I hope you will make your dream come true.
5. What is the computer used for
II .
1. though/although 2. places 3. capital 4. environment 5. outdoors
6. develop 7. harm 8. ever 9. required 10. solved
III.
More and more people have mobile phones in China. Mobile phones offer us a lot of convenience. We can call each other at any time, and also use them to send text messages. However , mobile phones bring us some trouble . We have to pay for it every month and using them too much is bad for our health. As a student , I think we should have mobile phones so that our parents can easily know what happened to us . But I don’t think it is right to keep mobile phones in classes .
Unit 4 Topic 2
Section A
I.1. in order to 2. on the earth 3. can’t wait to
4.will be realized/will come true 5.prefers; to
II 1.were discussed 2.will be driven 3.will be planted
4. in order to 5.will come true
选做题III.
1. patience 2. During 3. They 4. brushes 5. special
6. believe 7. tradition 8. when 9. Making 10. a
Unit 4 Topic 2
Section B
I. 1.discover 2. discoveries 3. discoverer 4. covered
5. discovered 6. invented 7. found out 8. found
II .1.will be finished 2.will be produced 3. will be built
should be mastered
III. 1. you heard the story about 2.It’s really cool.
3.I want to be a scientist when I grow up.
4. What does Mars look like
5. A wonderful movie will be shown tonight.
There will be/is going to be a wonderful movie tonight.
Unit 4 Topic 2
Section C
I. 1. was named after 2. weighs 3.travel 4.information
5.at a distance of 6.has been two days/ is two days 7.storm
II. 1. storm 2. weight 3. journey 4. screen 5. realized
6. dancer 7. described 8. astronaut
III. 1. planets 2. goes 3. before 4. read 5. angry
6. wrong 7. saw 8. millions of 9. anything 10. great
Unit 4 Topic 2
Section D
I.1.can’t wait to do sth. 2.admire sb. 3.discover something new
4.master computer skills 5.perform ballet 6.on the stage
7.at a distance of... 8.name after 9.limit the use of...
10.on the earth
II. 1.C 2.B 3. B 4. C 5. B 6. A
III .
In June, 2013, the spaceship Shenzhou X was successful sent into space. I was so excited and moved after watching it. I admire Chinese astronauts. So I want to be an astronaut when I grow up.
From now on, I decide to study hard on all the subjects especially science and English so that I can research and explore the space. What’s more, I must keep on keeping exercise in order to become an astronaut.
I hope my dream will be realized. I believe I can make it.
Unit 4 Topic 3
Section A
I. 1.who/that 2.which/that 3.which/that 4.who 5.that
II. 1. national 2. another 3. exploring 4. safely
proves 6. proud
III. 1.What a large crowd!
2.Who is the first Chinese to travel into space
3.All of you must be very proud.
Unit 4 Topic 3
Section B
I. 1.make up one’s mind to do sth. 2.advise sb. to do sth.
3.control the direction of spaceships
4.master computer technology
5.discover new ways 6.serve us better
7.change the speed 8.as well as
II . 1.What is the spaceship used for？
2.Spaceships are controlled by computers
3. How do the computers work
III. 1.A 2.C 3.A
Unit 4 Topic 3
Section C
I.1.There is no doubt 2.place cancel orders 3.brain
4.are connected by 5.tiny 6.inside 7.properly
II. 1.B 2.B 3.B 4. C
III. Preparing for meals is tiring. You may have to spend hour getting everything ready for cooking. Now in China, new mobile apps are here to help.
These apps provide you with meat, fish and vegetables, almost everything you need for a meal. You can order whenever you like and decide on the time for them to arrive. If you like, they can be washed, cut and packed for a certain dish. Some apps even guide you to cook step by step, making cooking easier.
Compared with the traditional way of going to the market, mobile apps save your time and energy. With such a new use of the mobile phone, you can enjoy a more relaxing life.
Unit 4 Topic 3
Section D
I. 1.certain；2.warns；3.tiny；4.housework；5. magazine 6.usual 7.personal
8.cancelled 9.connects 10.wives
II. 1. who/that is talking to Jim 2.that/which I borrowed, was written 3. no doubt 4. on his own 5.warned; not to 6.for certain
III.
The table tells us that 60% of the students think getting online is very helpful. They can get important information from the Internet, which is helpful to studies. They can make friends through the net. What’s more, it’s faster and cheaper to send e-mails on the Internet.
But 40% of them think that getting online is a waste of time and money. It is harmful to them because there is something bad for them to read. Besides, they never make real friends on the net, because they don’t know each other well. And they think they can phone or write to their friends if they want to.