語法復(fù)習(xí)五：強(qiáng)調(diào)句、It的用法、省略和插入語
3、在某些習(xí)慣說法中，可以代替人。
e.g. ---- someone is knocking at the door, peter. ---- who is it? ---- it’s me.
---- who are singing? ---- it is the children.
---- the light is still on in the lab. it must be the third-year students doing the experiment.
4、it與one的區(qū)別：這兩個(gè)詞都可以代表前面說過的名詞，但it用于同名同物的場合；one則用于同名異物的場合。
e.g. ---- 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與that的區(qū)別：兩詞都可代替某一特定名詞，但that指同一類，并非同一個(gè)。
e.g. the climate of south china is mild（溫和的）; i like it very much.（it指the climate of south china）
the climate of south china is much better than that of japan.（that指the climate）
（二）作無人稱代詞
it作無人稱代詞時(shí)，除了句中找不到它所代表的詞語外，另一個(gè)特點(diǎn)是它后面的內(nèi)容都是表示天氣、時(shí)間、距離、度量衡及情況等。
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?
（三）作強(qiáng)調(diào)詞，構(gòu)成強(qiáng)調(diào)結(jié)構(gòu)
用以幫助改變句子結(jié)構(gòu)，使句子的某一成分受到強(qiáng)調(diào)�！癷t is (was) + 所強(qiáng)調(diào)的成分 + that (who) + 其它成分�！痹谶@個(gè)句型中，it本身沒有詞義。詳見“一、強(qiáng)調(diào)句”。
（四）引導(dǎo)詞it作形式主語（賓語）
為了使句子平衡，常采用形式主語（或賓語）it ，而把真正的主語（或賓語）置于句子后面。通常引導(dǎo)詞it與它所代替的句子成分中間要夾有某些詞。
e.g. it takes half an hour to go there on foot.（it與to go there on foot之間夾有takes half an hour四個(gè)詞）
we thought it strange that mr smith did not come last night. （it與that從句中間夾有 strange）
但有時(shí)it與所替代部分之間并不夾有其它詞。
e.g. you may depend on it that they will support you.（因?yàn)榻樵~on之后一般不直接接that引導(dǎo)的賓語從句。注意：it不是多余的，不能當(dāng)作錯(cuò)句）
練習(xí)一、強(qiáng)調(diào)句、it的用法
1. my bike is missing. i can’t find ____ anywhere.
a. one b. ones c. it d. that
2. ---- who’s that? ---- ____ professor li.
a. that’s b. it’s c. he’s d. this’s
3. ____ was jane that i saw in the library this morning.
a. it b. he c. she d. that
4. ---- have you ever seen a whale alive? ---- yes, i’ve seen ____.