（人教版）高中英语选修八：Unit 5 Meeting your ancestors语言点及其练习

Unit 5 Meeting your ancestors语言点
学习目标
重点词汇
alternative, tentative, interrupt, 　　acute, 　 assume,　ample, primitive, analysis,　sharpen, somehow, applaud, accelerate, arrest　
　
重点短语
regardless of, 　at most, 　cut up,　　 be/ get fed up with, 　look ahead, 　date back to
重点句型
情态动词+ have done
if only
知识讲解
重点词汇
alternative
【原句回放】Can you think of the alternatives we would use today? 你们能想得出来今天我们用什么来替代这些东西吗？
【点拨】alternative n. 替换物
常用搭配：have no alternative but to do sth. 除......外别无选择；只有，只好
There are some alternatives to our plan.
有几种方案可以代替我们的计划。
He had no alternative but to go there alone.
他别无选择，只好一个人去那儿。
【拓展】alternative adj. 随便一个的；二者择一的，供替代的
The way was blocked, so we went by an alternative road.
这条路被挡住了，因此我们走了另一条路。
tentative
【原句回放】Make a tentative guess about what Peking Man may have done and used thousands of years ago. 试着猜猜几千年前“北京人”可能做的事情和使用的东西。
【点拨】tentative adj. 试探性的，不确定的
常用搭配：make a tentative suggestion提出试探性的建议
reach a tentative conclusion得出暂时的结论
He still held a tentative relationship with Mary.
他还和玛丽保持着若即若离的关系。
Could we make a tentative appointment for Friday?
我们能暂时先约在星期五吗?
【拓展】tentatively adv. 试探地，犹豫不决地
interrupt
【原句回放】I’m sorry to interrupt you but how could they live here? 很抱歉打断你，请问他们怎么能够生活在这个地方呢？
【点拨】interrupt vt. 阻断，打岔
常用搭配：interrupt the path 阻断道路
interrupt sb’s speech 打断某人的讲话
interrupt traffic 中断交通
interrupt the view 遮住视线
　　Traffic in the city was interrupted by a snowstorm. 城市交通被暴风雪阻断了。
　　Don’t interrupt me when I am busy. 我忙着时不要打扰我。
【拓展】 interruption n. 中断，打断，干扰
　　常用搭配：without interruption 不间断地, 继续不断地
　　The big earthquake caused the interruption of communication, traffic, service and so on.
　　大地震引起了通讯、交通、服务等等的中断。
　　Numerous interruptions have prevented me from finishing the work.
　　大量的干扰阻止了我完成工作。
acute
【原句回放】You are an acute observer. 你是个敏锐的观察者。
【点拨】acute adj. 敏锐的；严重的；深刻的
He suffers from acute depression.
他患有严重的抑郁症。
The housing shortage is more acute than first thought.
住房短缺比最初想的要严重。
Simon’s vague manner concealed an acute mind.
西蒙含糊的风格隐藏了他敏锐的头脑。
【拓展】常用短语：acute infection 急性感染
acute observer 敏锐的观察家
acute shortage 严重短缺
assume
【原句回放】So we think it is reasonable to assume they lived in these caves, regardless of the cold. 因此，我们有理由认为他们不顾严寒，就住在这些洞穴里。
【点拨】assume vt. 假定，设想；假装；呈现出；担任
常用搭配：assume a leading position 担任领导职务
assume a look of surprise 装出吃惊的样子
assume sb (to be) ...认为某人是……
It is generally assumed that...普遍认为……
I assume you always get up at the same time.
我想你总是在同一个时间起床。
Assuming it rains tomorrow, what shall we do?
假如明天下雨，我们怎么办呢？
　　He assumes a well-informed manner but in fact he knows very little.
　　他表现出一种见多识广的样子，实际上他几乎什么都不懂。
【拓展】assumption n. 假设，假想
常用搭配：make an assumption认为，假定
on the assumption that假定
　　His actions were based on a false assumption. 他的行为基于错误的设想。
ample
【原句回放】After that they would rub an ample amount of salt onto the skin to make it soft. 然后，他们可能在兽皮上擦上大量的盐，使皮变得很柔软。
【点拨】ample adj. 充足的，足够的，富裕的；宽敞的
We have ample money for the journey. 我们有足够的钱去旅游。
There’s ample room for the children on the back seat.
后座很宽敞足容得下孩子们。
He was reluctant to admit any of the ample evidence.
他对这些充分证据的任何部分都不愿承认其有效。
【拓展】amply adv. 足够地；详细地；充分地
ampleness n. 广大；富裕
amplify v. 放大，增强
primitive
【原句回放】Why, it’s a primitive necklace. Did early people really care about their appearance like we do? 哎呀，这是一条原始的项链吧。早期人类也像我们现在一样讲究外貌吗？
【点拨】primitive adj. 原始的，远古的，早期的；简单的，粗糙的
Primitive men made tools from sharp stones and animal bones.
原始人用尖石块和兽骨制造工具。
The natives of that region still live in primitive straw huts.
那个地区的居民依然住在古老的茅草屋里。
Small seashells were once used as a primitive kind of money.
小贝壳曾经被用作古老的钱币。
【拓展】primitively adv. 最初地；自学而成地
primitiveness n. 原始；原始性
analysis
【原句回放】Yes, indeed, as the botanical analyses have shown us, all the fields around here used to be part of a large shallow lake. 是的，确实是这样的，因为有关植物的分析已表明，周围所有的土地曾经是一个大浅水湖的一部分。
【点拨】analysis n. 分析 （复数：analyses）
常用搭配：on/ upon analysis 经分析
make an analysis of (=analyse) 分析
The analysis of the food showed the presence of poison.分析结果表明该食物有毒。
We made a careful analysis of his character.我们仔细分析了他的性格。
They carried out an analysis of this subject.他们对这个题目进行了分析。
On further analysis, the handsome young man was a cheat.
经过进一步分析之后发现这个英俊的年轻人是个骗子。
【拓展】analyse vt. 分析
He analysed the food and found it contained poison.
他对这种食物进行了化验，发现有毒。
sharpen
【原句回放】 It seems that they used sharpened stone tools to cut up animals and remove their skin. 看样子他们是用磨尖的石器来切割野兽并剥皮的。
【点拨】sharpen vt. & vi. （使）锋利；（使）尖锐；（使）清晰；（使技术）更高、更有效
Your knife needs sharpening. 你的小刀需要磨一磨了。
His speech served only to sharpen the differences between the two men.
他的讲话结果只是让两人之间的分歧更加严重。
The course will help students sharpen (up) their writing skills.
这门课程将有助于提高学生的写作能力。
【拓展1】sharp adj. 锐利的，锋利的，尖的；敏锐的；突然的；急剧的
adv. 准时地，整；突然地，急剧地
The famous writer is still sharp in thought though he has attained the age of ninety-two.
这位著名作家虽已九十二岁高龄,但仍然思维敏捷。
Recently there has been a sharp decline in interest in gardening throughout the town.
最近全镇对园艺的兴趣已急剧下降。
at seven o’clock sharp七点整
turn sharp to the left猛然向左转
【拓展2】词缀en-/ -en
词缀en-/ -en可以放形容词、名词等前或后，构成动词。如：
ripe 成熟的 → ripen 成熟，使熟
sure 确信的 → ensure 保证，使……安全
danger危险 → endanger 使……遭危险
courage勇气→ encourage 使……有勇气，鼓励
roll 名册→ enroll注册，记入名册
somehow
【原句回放】Somehow he cycled thirty miles to Dr Black because there was no alternative means of transport. 他骑自行车走了30英里给布莱克博士看，因为没有可供选择的其他交通方式。
【点拨】somehow adv. 以......方式；不知怎么地
　　I think she’s wrong but somehow I’m not completely sure.
　　我认为她错了，但是不知怎么不很肯定。
　　She somehow got lost where she grew up. 她不知怎么在出生的地方却迷路了。
You must make up for the lost time somehow. 你必须以某种方式把损失的时间补上。
【拓展】anyhow adv. 不管怎样，无论如何，相当于in spite of that, in any case。
　　It may rain, but anyhow I shall go out. 可能下雨，但无论如何我要出去。
applaud
【原句回放】She had felt so proud as the group shouted loudly to applaud his choice. 当族人为他（大胡）的选择欢呼鼓掌的时候，她（拉拉）觉得非常自豪。
【点拨】applaud vt. & vi. 鼓掌欢迎，称赞
Everyone applauded when the play ended. 戏落幕了，每个人都鼓起掌来。
The crowd applauded him the performance for five minutes.
群众为他的演出鼓掌五分钟。
　　The residents in the neighborhood all applauded the council’s decision to close the small dye factory. 社区的居民们都称赞理事会关掉小染坊的决定。
【拓展】applause n. 鼓掌欢迎，喝彩
　　常用搭配：give sb. applause for sth. 因……给某人鼓掌
　　 win applause 赢得喝彩
accelerate
【原句回放】... Lala accelerated her walk up the path to the caves fearing that there might be wild beasts lying in wait for her. ...... 拉拉加快了走向洞穴通道的步伐，一边害怕可能有野兽躺在那里等着她。
【点拨】accelerate vt. & vi. 加速，促进；催促
　　The driver stepped on the gas and accelerated the car.
　　司机踩了油门，汽车加速了。
　　Those economic policies have accelerated the decline of manufacturing industry.
　　那些经济政策加速了制造业的衰退。
【拓展】acceleration n. 加速, 加速度
　　　　accelerator n. 加速者, 加速器
　　This bus has good acceleration. 这辆公交车有良好的加速能力。
arrest　
【原句回放】She had almost reached her destination when a delicious smell arrested her progress and she stopped. 快到目的地的时候，一阵香气扑鼻，她不往前走了，停了下来。
【点拨】arrest vt. 逮捕；吸引；制止
常用搭配：arrest sb. for因……而逮捕某人
get arrested遭逮捕
arrest one’s attention引起注意
He was arrested by policemen for theft. 他因偷窃被警察逮捕。
The doctor arrested the growth of the disease. 医生阻止了病情恶化。
Our attention was arrested by the sound of a shot. 枪声引起了我们的注意。
The bright colors of the flowers arrested Susan’s attention.
花的艳丽色彩引起苏珊的注意。　
【拓展】arrest n. 逮捕，拘留；阻止
常用搭配：under arrest被捕
make an arrest进行拘捕
The police made three arrests yesterday. 警察昨天执行了三项逮捕行动。

重点短语
【Unit 5 Meeting your ancestors词语精讲】
regardless of
【原句回放】So we think it is reasonable to assume they lived in these caves, regardless of the cold. 因此，我们有理由认为他们不顾严寒，就住在这些洞穴里。
【点拨】regardless of不管，不顾
Regardless of danger, he climbed the tower.
尽管有危险，他还是爬上了那座塔。
He continued speaking,?regardless of?my feelings on the matter.
他继续说着，也不顾我对这事的感受。
【拓展】意义相同的表示法：
in spite of despite
at most
【原句回放】It’s at most three centimeters long. 这个东西最多三厘米长。
【点拨】at most 至多
It will take two hours at most to get there.
最多两个小时就到那儿了。
There were?at most?twenty people in the classroom.
教室里最多就20个人。
【拓展】反义词：at least 至少
cut up
【原句回放】It seemed that they used sharpened stone tools to cut up animals and remove their skin. 看样子他们用磨尖的石器来切割野兽并剥皮。
【点拨】cut up 切碎, 受损, 使痛苦
趣味记忆：cut 表示“切”；up 表示“穷尽”，所以cut up表示“切碎”；而有人用小刀剌某人的心，应该是“痛苦不堪的”，所以cut sb. up表示“make sb. feel sorrow or suffer all the time”。
Cut up the carrots before you put them into the pot.
把胡萝卜放进锅里前要切碎。
Their house was badly?cut up?in the bombing.
在轰炸中他们的房子严重受损。
She is very?cut up?about her father’s death.
由于父亲的去世，她非常痛苦。
【拓展】含cut的短语
cut away 切除, 剪掉 cut down 削减, 压缩 cut in 插进来说, 插嘴
cut off 切断，隔绝 cut out 删掉 剪下,切除
fed up with
【原句回放】Well, I’m fed up with all the attention, and ... 哎，我已厌倦了备受关注，并且......
【点拨】be/get fed up with 对……厌烦
趣味记忆：feed的过去式和过去分词是fed，表示“喂养”；up 表示“完全地、彻底地”； with表示“用”，用某物把某人都喂得满满的了，都顶了，当然就恶心得都“厌烦”了。此短语是feed sb. up with sth.的被动形式，相当于系表结构，表示状态。
I’m fed up with this wet weather. 这么潮湿的天气，我都烦死了。
People got?fed up with?all these traffic jams. 人们对于交通堵塞都烦透了。
【拓展】两个易混短语：
be tired of 对......厌烦 be tired from 因为......而劳累
look ahead
【原句回放】If only she had looked ahead and planned better this year! 她今年要是早有预见，计划得更好些就好了！
【点拨】look ahead 向前看，考虑到将来（ahead表示“在前”，有“future”之感）
We must look ahead before we make a decision.
我们做决定前必须考虑到将来。
We should?look ahead?and spare a thought for future generations.
我们应该着眼于未来，考虑到我们的后代。
date back
【原句回放】All the objects are from the same excavation site in Sanxingdui and can be dated back to between 3,000 and 5,000 years ago. 所有物品来自三星堆同一处古迹，可以追溯到3000到5000年前。
【点拨】date back to 追溯到……
Oxford and Cambridge date back to the thirteenth century.
牛津和剑桥的历史要追溯到13世纪。
These plant fossils?date back to?the age of the dinosaurs.
这些植物的化石要追溯到恐龙时代。
【拓展】同义短语：date from 始于
A friendship between us dated from twenty years ago.?　
我们两个的友谊始于20年前。■
　
重点句型
情态动词+ have done
【原句回放】It must have been very uncomfortable. 那一定很不舒服。
【点拨】情态动词﹢have done
表示对过去的推测或表示过去做了不该/需做的事。常见的有:
　　1. can/could have done
① 肯定句中表示“过去本来能做，结果却没有做”；
② 否定句、疑问句中表示对过去发生的行为的猜测。
　　We could have walked to the station; it was too near. 我们本来能走到车站的，太近了。
　　He couldn’t have finished the job, for the time is too short.
　　他不可能做完工作了，因为时间太短。
　　2. should/ought to have done
① 肯定句中表示“过去本应该做某事，结果却没有做”；
② 否定句中则表示“本不该做某事，反而做了”。
　　You should have been here five minutes ago, because the meeting has begun.
　　你五分钟前就该在这里，会议已经开始了。
3. must have done
表示“过去一定做了某事”，只能用于肯定句。
　　It must have rained last night, for the ground is wet. 昨晚一定下雨了，地面是湿的。
　　4. may/might have done
　　表示“或许/可能已经做了某事”,常用于肯定句或否定句，不用于疑问句，might表示语气更加不肯定。
　　It’s too late. I think he may have gone to bed. 太晚了，我想他可能已经上床睡觉了。
　　5. needn’t have done
　　表示“本不必做某事而实际上已经做了”。
　　对比：
　　didn’t need to do 表示“过去不需要做某事，实际上也没有做”。
　　Your home is not far from your school, so you needn’t have left in such a hurry yesterday.
　　你家离学校不远，所以你昨天不需要那么着急离开。（事实上“you”昨天匆忙离开了）
　　I didn’t need to hand in my paper to my teacher the next morning, so I left very early.
　　我第二天不需要交卷子，所以我很早就离开了。（实际上也没有交）
　　6. would rather have done
　　表示“宁愿当时做了某事”，其否定形式would rather not have done表示“宁愿当时没有做某事”。
　　I would rather have followed her advice. 我宁愿当时听了她的劝告。
if only
【原句回放】If only she had looked ahead and planned better this year! 她今年要是早有预见，计划得更好些就好了！
【点拨】if only但愿……；要是……就好了
　　if only引出一种愿望，谓语动词一般用虚拟语气，具体形式：
　　1. could/ would do表示对将来事情的愿望；
2. 用一般过去式（be用were）表示与目前或现在事实相反的愿望；
　　3. had done表示与过去相反的愿望。
　　I’m worried about the coming exams. If only I could have time to review my lessons.
我对即将到来的考试非常担心。如果我有时间复习该有多好啊。
If only I had a car, I could get out of the place.
要是我有辆汽车，我就能离开这个地方了。
　　If only I hadn’t spent so much time before TV then.
　　要是那时我不在电视前面呆那么长时间就好了。
巩固练习
一、单词填空
根据句意及所给首字母或汉语提示用本课单词的正确形式完成句子。
1．As there is less and less coal and oil，scientists are exploring new ways of making use of a_________ energy，such as sunlight，wind and water for power and fuel.
2．It is generally a_________ that stress is caused by too much work.
3．He will be put into prison if there is a________ evidence to prove his guilt.
4．It was only later that we realized the true s________ of his remark.
5．He could have finished it on schedule，but s_________ he fell behind.
6．After his wonderful performance, the audience stood up and a___________ him for a long time.
7．She had almost reached her destination when something __________(抓住) her attention and she stopped.
8．We must seize this opportunity and take proper measures to __________(加速) the growth of our economy.
9．He had a headache and went to the chemist’s to get something for his pain __________(减轻)．
10．Many parents opposed the__________(划分) of the classes into different sets.
二、选词填空
从下面方框中选出适当的短语并用其正确形式填空。
regardless of, 　at most, 　cut up,　　 be fed up with, 　look ahead, 　
date back to, lie in wait for, keep out, arrest sb. for, if only
1．__________，we must expect some changes to be made in our system of government.
2．The amount will be paid to everyone __________ whether they have children or not.
3．She ___________ the meat on her plate and put them into her son’s plate.
4．The robbers were __________ me as I came out of the bank.
5．Don’t go to join them. You could ____________ stealing cars.
6．This is an old building ____________ the 16th century.
7．The notice hanging on the front wall is meant to __________ the unwanted visitors，especially at working hours.
8．__________ his boring speech, I decided to slip out silently.
9．__________ the whole family could be united during the Spring Festival！
10．Instead he should be there punctually or _________ a few minutes after.
三、单项选择
1. The bell_______ the end of the period rang, _______ our heated discussion.
A. indicating, interrupting　　　B. indicated, interrupting
C. indicating, interrupted 　　　D. indicated, interrupted
2. Let’s ______ that there’s a selection this month. What’s the result likely to be, given the latest opinion polls?
A. assume　　　 B. announce 　　　C. assist 　　　D. approve
3. _______, I don’t feel I can trust him. He did nothing wrong, though.
A. Anymore 　　　B. Somewhat　　　 C. Somehow　　　 D. Anyhow
4. As we all know, being exposed to the sun can _______ the aging process of our skin.
A. release 　　　B. accelerate 　　　C. resist 　　　D. accumulate
5. Tim continued to run away, _______ our shouts to him that he should return.
A. as regards　　　B. with regard to C. regardless of　　 D. regarding
6. The tower _______ the Warring States is well worth visiting.
A. dated from 　　　B. dated back from　　　 C. dating from　　　 D. to date from
7. My sister met him at the Grand Theater yesterday afternoon, so he _____ your lecture.
A. couldn’t have attended 　　　B. needn’t have attended
C. mustn’t have attended　　　　D. shouldn’t have attended
8. Look at the trouble I am in! If only I _______ your advice.
A. followed　　　 B. would follow 　　　C. had followed　　　 D. should follow
9. I’m afraid I have no _______ but to ask you to leave school.
A. substitute 　　　B. alternative 　　　C. opportunity 　　　D. objective
10. The flowers on the hill ________ her attention the moment she got off the car.
A. fixed 　　　B. paid　　　 C. arrested　　　 D. put
11. Planning officials are now looking _______ to the needs of the population in the year 2017.
A. back 　　　B. ahead　　　 C. up 　　　D. down
12. The meat should be ______ into small pieces before cooking; otherwise it will be difficult to cook.
A. cut out 　　　B. cut off 　　　C. cut up 　　　D. cut down
13. He makes it a rule to listen to English news on the radio _________ once a day.
A. at last B. at first C. at least D. at most
14. In __________ times human being did not travel for pleasure but to find a more favourable climate.
A. prime B. primitive C. primary D. previous
15. They carried out the ________ of the cause of the problem.
A. analysis B. storage C. stress D. significance
16. The schoolmaster ________ the girl’s bravery in his opening speech.
A. applauded B. appointed C. clarified D. clapped
17. My brother said that he was ________ his rude boss, and decided to resign.
A. fed up with B. put up with C. adapted to D. used to
18. The girl was not very happy, so she had to give us a ________ smile.
A. sweet B. amused C. cheerful D. tentative
19. ________ sunshine and rainfall are bringing the crops on nicely.
A. Dizzy B. Ample C. Enough D. Precious
20. We should _________ the competitive edge of our goods and services for export by ensuring good quality.
A. sharpen B. assume C. distribute D. deserve
答案与解析：
一、单词填空
1.alternative　 2.assumed　 3.ample　 4.significance 5. somehow　
6.applauded　 7.arrested　 8. accelerate　 9.relief 10．division
疑难解析：
4. significance（意义，重要性）；句意：到晚些时候我们才意识到他的话的真正的意义。
5. 句意：他本能够准时（on schedule）完成，但是不知怎么的，他落后了。
8. 句意：我们必须抓住机会采取合适的措施来加速（accelerate）我们经济的增长。
10. division是divide的名词，表示“分割，划分”。set 意思是“一组”。
二、选词填空
1.Looking ahead　2.regardless of　3.cut up 4. lying in waiting for　 5. be arrested for
6. dating back to 7. keep out 8. Fed up with 9. If only 10. at most
疑难解析：
4.lie in wait (for sb) 埋伏着等待，窥伺，潜伏以待。
6. date back to 表示“追溯于”，与an old building是主动关系，因为已经有谓语is，用动词-ing形式作定语。
8. 因为句子有谓语，be fed up with...在句子中表示原因，要去掉be，用过去分词作状语。
三、单项选择
1. A。动词“indicate（标明）”与所修饰词“the bell”是主动关系，用v-ing形式作定语；由“铃声打断了我们的讨论”可知“interrupt”与句子主语是主动关系，用v-ing形式作结果状语。
2. A. given表示“考虑……”的意思。assume 假设，猜想；announce 宣布；assist 帮助；approve 赞成。句意：我们假设本月会有一次选拔，根据最近的民意调查，结果可能什么样呢？
3. C。句意：不知怎的，我感觉不能相信他，虽然他什么错事也没有做。somehow 以某种方式，不知怎么地；somewhat 稍微，有点；anymore（不）再； anyhow 不管怎么说，无论如何。
4. B。句意：我们都知道，阳光暴晒会加速皮肤老化。release 释放，排放；resist 抵抗；accumulate 积累。
5. C。句意：Tim继续逃跑，也不管我们喊让他回来。regardless of 不管，不顾；as regards 关于，至于；with regard to 关于；regarding 关于，就......而论。
6. C。句中已有谓语动词，空白处要作定语；date from 意为“始自”，与所修饰词“The tower”是主动关系，不能用被动语态，所以用v-ing形式作定语。
7. A。couldn’t have attended意为“不可能参加了”，对过去事实的否定的推测。must表示推测只用于肯定句中。
8. C。if only后面所接的句子要用虚拟语气, 表示与过去事实相反,用过去完成时，有“后悔遗憾”之意。句意：看我现在的处境,要是我当时接受你的建议就好了。”言外之意,当时没有接受建议。
9. B。substitute 代替物；alternative 两者择一，可选择的事物；opportunity 机会；objective 目的，目标。
10. C。arrest one’s attention 吸引了某人的注意；pay/fix attention to sb./ sth. 注意某人/某物。
11. B。look ahead to 展望，向前看。从“做计划的官员”和“2017”可知。
12. C。cut up 切碎；cut out 停止，删掉，切掉。cut off 切断，隔离；cut down 消减。
13. C。本题考查at开头的短语。at last 最后；at first 起初；at most 至多；at least 至少。多听英语新闻对学习英语有益处，所以选at least；而最多听一次作为规定没有意义，at most不合题意。
14. B。primitive 原始的。句意：在原始时代，人类旅行不是为了找乐趣，而是为了寻找更有利的气候。prime 首要的；primary 最初的；previous 先前的，以前的。
15. A。句意：他们完成了那个问题的原因分析。analysis 分析；storage 贮藏，保管；storage贮存；stress 压力，强调，重要性；significance 重要性，意义。
16. A。applaud 意为“称赞，鼓掌”。句意：校长在开幕词中称赞了这位姑娘的勇敢。appoint 约定，任命；clarify 澄清；clap 拍手，鼓掌（clap接的宾语一般是承受“拍”这一动作的人或物）。
17. A。因为“受够了（be fed up with）”粗鲁的老板，所以决定辞职。put up with 表示“忍受”，用被动语态不合题意，注意句中的was；adapt to 适应，改编。
18. D。tentative 试探性的，尝试的，暂时的。句意：那个女孩不太高兴，所以她只向我们勉强地笑了笑。sweet 甜蜜的；amused 喜悦的；cheerful 快乐的；上述三选项与句意不符。
19. B。句意：充足的阳光和雨水正使庄稼茁壮地生长。ample 表示“足够的，丰富的，大量的”，强调“充裕”；enough 也表示“足够的”，强调“够量”，不合题意；dizzy 晕眩的；precious 珍贵的。
20. A。句意：我们应该坚持以质取胜，提高出口商品和服务的竞争力。sharpen（使）提高，改善；assume 假装，承担；distribute 分配，分布；deserve 应得。