Unit 6 Section Ⅲ Grammar（教师用书word）-2022-2023学年新教材高中英语选择性必修第二册【精讲精练】北师大版

Section Ⅲ　Grammar it 用法及used to、would用法 一、it 用法 1．作人称代词 (1)it代替前面(或后面)的单数名词或分句等所表示的事物。 Although we cannot see it，there is air all around us. (it代替后面的air) 空气总是在我们周围，尽管我们看不见它。 They say he has left the town, but I don't believe it. (it代替前面They...town分句中的情况) 他们说他已经离开了乡镇，但是我不相信。 (2)代替有生命但不能或不必分阴阳性的东西(包括婴儿)。 Yesterday we saw a big tree.It was fully twenty metres high. (it代替前面的tree) 昨天我看见一颗大树。它足足有二十米高。 The baby cried because it was hungry. (it代替前面的baby) 婴儿哭了，因为他/她饿了。 (3)在某些习惯说法中，可以代替人。 —Who are singing? —It is the children. —The light is still on in the lab. —It must be the third­year students doing the experiment. (4)it与one的区别：这两个词都可以代表前面说过的名词，但it用于同名同物的场合；one则用于同名异物的场合。 —Do you still have the bicycle? —No，I have sold it. —Is this knife yours？ —No.It is Xiao Zhang's.Mine is the one on the desk. (5)it与that的区别：两词都可代替某一特定名词，但that指同一类，并非同一个。 The climate of South China is mild(温和的); I like it very much.(it指the climate of South China) The population of shanghai is larger than that of Beijing.(that指the population) 2．作无人称代词 it作无人称代词时，除了句中找不到它所代表的词语外，另一个特点是它后面的内容都是表示天气、时间、距离、度量衡及情况等。 It is fine (rainy, windy, etc.). It is noon. It is a half hour's walk to the factory. It is eighteen square metres in area. What does it matter? 3．作强调词，构成强调结构 用以帮助改变句子结构，使句子的某一成分受到强调。在这个句型中，it本身没有词义。 句型结构：It is (was) ＋ 所强调的成分 ＋ that (who) ＋ 其他成分。 It is by listening to and understanding each other that problems between parents and children can be settled. 只有通过相互倾听和相互理解，孩子和父母之间的问题才能被解决。(强调方式状语) It was Paul who/that broke the window just now. 刚刚是保罗打破了窗户。(强调主语) 4．引导词it作形式主语(宾语) 为了使句子平衡，常采用形式主语(或宾语)it ，而把真正的主语(或宾语)置于句子后面。通常引导词it与它所代替的句子成分中间要夹有某些词。 常见形式主语或形式宾语，代替不定式、动词­ing形式或从句。 (1)it作形式主语的常用句型： ①It＋be＋adj./n.＋(for/of sb)＋to do sth ②It is no good/use/useless doing sth ③It's (well) worth doing... ④It＋be＋名词词组(a pity/a fact/no wonder/...)＋that从句 ⑤It＋不及物动词(词组)(seem/appear/turn out/occur to sb/...)＋that从句 ⑥It＋be＋过去分词＋that从句 ⑦It takes sb time/money to do sth It is obvious to the students that they should get