外研版（2019）选择性必修第二册 Unit4 Breaking boundaries语法-精讲学案（有答案）

Unit4 语法-精讲破
It作形式主语
一、作形式主语替代主语从句
观察
1.It is quite certain that he will be at the meeting.
2.It is important that we（should）think before we decide.
3.It is a pity that you missed the sports meeting last week.
4.It is reported that 16 people were killed in the earthquake.
5.It is required that the students（should）learn a foreign language.
6.It seems that they know what they’re doing.
归纳 It替代主语从句作句子主语，主语从句后置。
常见的句型有：
（1）“It+be+形容词+that从句.”可用于此句型的形容词有 wonderful、true good、right、wrong、Important、surprising clear、certain、necessary等。需要注意的是，当形容词是important、necessary等时，从句要用1._______，谓语动词用should+动词原形”，should可以省略。
（2）“It+be+名词（词组）+that从句”适用该句型的名词（词组）有 a pity，an honour、a good thing，a fact、a surprise等。
（3）“It+be+过去分词+that从句”适用该句型的过去分词有 announced、believed，expected、hoped、decided、reported、 said、shown等。需要注意的是，当过去分词是 suggested、required、ordered等时，从句要用2._______，谓语动词用“should
+动词原形”，should可以省略。
（4）还可用于“It seems/appears+that从句.”句型中。
二、作形式主语替代不定式短语
观察
1.It is brave of the doctors and nurses to save people infected with the coronavirus.
2.It is important (for you) to remember that Ebola doesn’t respect national boundaries.
3.But it is vital（for you）not to take any chances.
归纳 （1）It is kind（brave/foolish/….3._______ sb.）to do sth.不定式的逻辑主语是由of引出的，句中的形容词必须是能表示逻辑主语特征的褒义或贬义形容词。
（2）It is necessary（important/vital/…4.______ sb.）to do sth.不定式的逻辑主语是由for引出的，句中的形容词通常是表示重要性、紧迫性、频繁程度等情況的形容词。
三、作形式主语替代动名词短语
观察
1.It is no good/no use learning English without speaking English.
2.It's useless trying to argue with Shylock.
3.It’s a waste of time talking to her any more.
归纳 It作形式主语，可以替代后面的动名词短语。常用于“It+be+名词或形容词+动名词短语.”句式中，这类名词和形容词常常是good、5._____、6._____、a waste of time、senseless、7、______等。
链接高考
单句语法填空
1.（2017江苏，阅读理解D，★★☆）When it comes to adaptation，it is important
__________（understand）that climate change is a process.
2.（2017浙江，阅读理解A，★★☆）While it’s likely ______ he understood very little of the books they were his introduction to classical paintings.
3.（2016课标全国I，语法填空，★★☆）So It was a great hone ______ (invite) backstage at the not-for-profit Panda Base where ticket money helps pay for research.
句型转换
4.、（2020浙江1月，阅读理解A改编，★★☆）That you'd read every word in the book and needed another to start made no difference to her.
→_____ _____ _____ _____ to her that you'd read every word in the book and needed another to start.
5.（★★★）It is reported that a space station will be built on the moon in years to come. →A space station _____ _____ _____ _____ _____ on the moon in years to come.
6.（★★☆）It is said that body language accounts for 55 per cent of a first impression while what you say just 7 per cent.
→ Body language _____ _____ _____ _____ _____ 55 per cent of a first impression while what you say just 7 per cent.
7.（★★★）Keep in mind that to waste food is a shame
→ Keep in mind that _____ _____ _____ _____ _____ _____ _____.
8.（★★☆）Crying over spilt milk is of no use.
→_____ _____ _____ _____ _____ over spilt milk.
完成句子
9.（2018北京，阅读理解D，★★☆）很难预测无人驾驶汽车什么时候会遍布我们的道路上的各个地方。
_____ _____ _____ _____ when driverless cars will be everywhere on our roads.
10.（2018天津，8，★★☆）他花了很长时间掌握成为一名优秀舞蹈家所需要的技能。
_____ _____ _____ _____ _____ _____ to acquire the skills he needed to become a good dancer.
答案：
1.虚拟语气2.虚拟语气3.of 4.for 5.no good
6.no use7. useless
1.to understand考查非谓语动词。句意：当提到适应时，了解气候变化是一个过程很重要。第二个it为形式主语，to understand..真正的主语。
2.that考查名词性从句。句意：虽然他可能对这些书了解甚少，但它们是他对古典绘画的初次接触。it为形式主语，that引导的从句为真正的主语。由于从句结构完整，句意完整，因此使用that。
3.to be invited考查非谓语动词。it为形式主语，to be invited..真正的主语。
4.It made no difference
5. is reported to be built
6. is said to account for
7.it is a shame to waste food
8.It is no use crying
9.It's hard to predict
10.It took him a long time
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