（19）it的用法
it可用作人稱代詞、指示代詞、先行詞及引導(dǎo)詞等。
1. 人稱代詞it，是第三人稱單數(shù)中性，代表前文已提到過(guò)的一件事物。如：
1）That vase is valuable. It's more than 200 years old. 那個(gè)花瓶很珍貴，它有200多年的歷史。
2）I love swimming. It keeps me fit. 我喜歡游泳，它能使我保持健康。
當(dāng)說(shuō)話者不清楚或無(wú)必要知道說(shuō)話對(duì)象的性別時(shí)，也可用it來(lái)表示。 如：
3）It's a lovely baby. Is it a boy or a girl？ 寶寶真可愛(ài)，是男孩還是女孩？
it可用來(lái)指代團(tuán)體。如：
4）The committee has met and it has rejected the proposal. 委員會(huì)已開(kāi)過(guò)會(huì)，拒絕了這項(xiàng)建議。
it用以代替指示代詞this， that.如：
5）—— What's this？ —— It's a pen. —這是什么？ —是一支鋼筆。
6）—— Whose book is that？ —— It's Mike's. —那是誰(shuí)的書(shū)？ —是邁克的。
2. 指示代詞it，常用以指人。如：
7）Go and see who it is. 去看看是誰(shuí)。
8）—— Who is making such a noise？ —是誰(shuí)發(fā)出這樣的吵鬧聲？
—— It must be the children. —一定是孩子們。
3. 虛義it無(wú)指代性，常用作沒(méi)有具體意義的主語(yǔ)，出現(xiàn)于表示天氣、氣候、溫度、時(shí)間、地點(diǎn)、距離等意義的句子中。如：
9）It is half past three now. 現(xiàn)在是三點(diǎn)半鐘。
10）It is six miles to the nearest hospital from here. 這里離最近的醫(yī)院也有六英里。
11）It was very cold；it snowed and grew dark. 天氣很冷；天下著雪，漸漸地變黑了。
it也常用來(lái)表示一般的籠統(tǒng)的情況。如：
12）It's awful—I've got so much work I don't know where to start. 糟透了——我有這么多工作要做我不知從何開(kāi)始。
13）How is it going with you？ 你近況如何？
14）Take it easy. 不要緊張。
it也常用于下列結(jié)構(gòu)：
15）It looks as if the college is very small. 看起來(lái)這個(gè)學(xué)院很小。
16）It seems as though our plan will be perfect. 似乎我們的計(jì)劃很完善。
17）It's my turn. 該輪到我了。
it也常用于某些習(xí)慣用語(yǔ)中作賓語(yǔ)，各該習(xí)慣用語(yǔ)有具體意義，但it并無(wú)具體意義。如：
cab it 乘車 catch it 受責(zé)，受罰 come it 盡自己分內(nèi) come it strong 做得過(guò)分 walk it 步行
make it 辦成 take it out of somebody 拿某人出氣
4. 先行詞it.
it充當(dāng)形式主語(yǔ)或形式賓語(yǔ)，本身無(wú)意義，只起一種先行引導(dǎo)的作用，先行詞不重讀。后面的真正主語(yǔ)或真正賓語(yǔ)通常是不定式結(jié)構(gòu)、-ing分詞結(jié)構(gòu)或名詞性從句。
（1）用作形式主語(yǔ)
18）It is difficult to translate this article. 翻譯這篇文章很難。
19）It is getting harder every day for a lazy man to get a living. 懶漢謀生是日益困難了。
20）What time would it be most convenient for me to call again？什么時(shí)候我再給你打電話最合適？
21）It is no use going there so early. 這么早去那里沒(méi)有用。
22）It has been a great honour your coming to visit me. 你的來(lái)訪是我很大的榮幸。
23）It is strange that he did not come at all. 真奇怪，他竟還沒(méi)來(lái)。
24）It doesn't matter what you do.什么都沒(méi)關(guān)系。
在上述諸例中，后置的真正主語(yǔ)可以取代先行it的位置，而出現(xiàn)于句首。
To translate this article is difficult.
Going there so early is no use.
That he did not come at all is strange.
上述結(jié)構(gòu)遠(yuǎn)不如用先行it結(jié)構(gòu)普通。此外，也并非所有先行it結(jié)構(gòu)都可作上述轉(zhuǎn)換。如：
25）It seems that John is not coming after all. 似乎約翰終竟不來(lái)。
26）It happened that John was the only witness. 碰巧約翰是的證人。
上述兩例只能轉(zhuǎn)換為：
John doesn't seem to be coming after all.
John happened to be the only witness.
（2）用作形式賓語(yǔ)
27）I found it difficult to explain to him what happened. 我覺(jué)得向他解釋清發(fā)生了什么事很困難。
28）He thought it no use going over the subject again. 他認(rèn)為再討論這個(gè)問(wèn)題沒(méi)有用了。
29）They kept it quiet that he was dead. 他們對(duì)他的死保密。
30）We must make it clear to the public that something should be done to stop pollution.
我們必須使公眾明白應(yīng)該采取措施制止污染。
5. 分裂句引導(dǎo)詞it.
分裂句是以it為引導(dǎo)詞的強(qiáng)調(diào)句型。它的結(jié)構(gòu)形式是：It+be的一定形式+中心成分+that-/who-從句。如：
31）It was Jane that/who called this morning. 是珍妮今天上午打來(lái)電話。
32）It was a parcel that she brought him. 她帶給他的是一個(gè)包裹。
分裂句是由普通陳述句轉(zhuǎn)換而來(lái)的。通過(guò)這種結(jié)構(gòu)可以強(qiáng)調(diào)除謂語(yǔ)動(dòng)詞以外的大多數(shù)句子成分。如：
33）John gave Mary a handbag at Christmas. 約翰在圣誕節(jié)給了瑪麗一個(gè)提包。
根據(jù)上下文和語(yǔ)義意圖，說(shuō)話人可以通過(guò)分裂句分別強(qiáng)調(diào)主語(yǔ)、間接賓語(yǔ)、直接賓語(yǔ)、狀語(yǔ)，使之成為信息中心。
34）It was John that/who gave Mary a handbag at Christmas. 是約翰在圣誕節(jié)給了瑪麗一個(gè)提包。
35）It was Mary that John gave a handbag （to） at Christmas. 約翰在圣誕節(jié)是給瑪麗提包的。
36）It was a handbag that John gave Mary at Christmas. 約翰在圣誕節(jié)給瑪麗的是一個(gè)提包。
37）It was at Christmas that John gave Mary a handbag. 是在圣誕節(jié)約翰給了瑪麗一個(gè)提包。
分裂句的時(shí)態(tài)一般應(yīng)一致，即主句與從句的時(shí)態(tài)應(yīng)皆用現(xiàn)在時(shí)，或皆用過(guò)去時(shí)，或皆用將來(lái)時(shí)。如：
38）It is not I who am angry. 發(fā)怒的不是我。
39）It was my two sisters who knew her best. 是我的兩個(gè)姐妹最了解她。
40）It will not be you who will have to take the blame for this. 對(duì)此須受責(zé)難的將不是你。
有時(shí)分裂句的謂語(yǔ)動(dòng)詞還可以采取復(fù)雜形式。如：
41）It may have been at Christmas that John gave Mary a handbag. 可能是在圣誕節(jié)約翰給瑪麗一個(gè)提包。
42）It might have been John who gave Mary a handbag. 很可能是約翰給了瑪麗一個(gè)提包。
分裂句可以強(qiáng)調(diào)多種多樣的狀語(yǔ)成分。如：
43）It was when she was about to go to bed that the telephone rang. 是在她即將上床睡覺(jué)時(shí)電話鈴響了。
44）It was because I wanted to buy a dictionary that I went to town yesterday. 我昨天是由于想買一本詞典而進(jìn)城的。
45）It was not until his father came back that Tom went to bed yesterday. 昨天湯姆是直到他父親回來(lái)才上床睡覺(jué)的。（注意句中not的位置）
主語(yǔ)補(bǔ)語(yǔ)通常不可以用作分裂句的中心成分，如在規(guī)范英語(yǔ)中通常不說(shuō)：
It is beautiful that she is.
It is chairman of the Committee that he is.
it可用作人稱代詞、指示代詞、先行詞及引導(dǎo)詞等。
1. 人稱代詞it，是第三人稱單數(shù)中性，代表前文已提到過(guò)的一件事物。如：
1）That vase is valuable. It's more than 200 years old. 那個(gè)花瓶很珍貴，它有200多年的歷史。
2）I love swimming. It keeps me fit. 我喜歡游泳，它能使我保持健康。
當(dāng)說(shuō)話者不清楚或無(wú)必要知道說(shuō)話對(duì)象的性別時(shí)，也可用it來(lái)表示。 如：
3）It's a lovely baby. Is it a boy or a girl？ 寶寶真可愛(ài)，是男孩還是女孩？
it可用來(lái)指代團(tuán)體。如：
4）The committee has met and it has rejected the proposal. 委員會(huì)已開(kāi)過(guò)會(huì)，拒絕了這項(xiàng)建議。
it用以代替指示代詞this， that.如：
5）—— What's this？ —— It's a pen. —這是什么？ —是一支鋼筆。
6）—— Whose book is that？ —— It's Mike's. —那是誰(shuí)的書(shū)？ —是邁克的。
2. 指示代詞it，常用以指人。如：
7）Go and see who it is. 去看看是誰(shuí)。
8）—— Who is making such a noise？ —是誰(shuí)發(fā)出這樣的吵鬧聲？
—— It must be the children. —一定是孩子們。
3. 虛義it無(wú)指代性，常用作沒(méi)有具體意義的主語(yǔ)，出現(xiàn)于表示天氣、氣候、溫度、時(shí)間、地點(diǎn)、距離等意義的句子中。如：
9）It is half past three now. 現(xiàn)在是三點(diǎn)半鐘。
10）It is six miles to the nearest hospital from here. 這里離最近的醫(yī)院也有六英里。
11）It was very cold；it snowed and grew dark. 天氣很冷；天下著雪，漸漸地變黑了。
it也常用來(lái)表示一般的籠統(tǒng)的情況。如：
12）It's awful—I've got so much work I don't know where to start. 糟透了——我有這么多工作要做我不知從何開(kāi)始。
13）How is it going with you？ 你近況如何？
14）Take it easy. 不要緊張。
it也常用于下列結(jié)構(gòu)：
15）It looks as if the college is very small. 看起來(lái)這個(gè)學(xué)院很小。
16）It seems as though our plan will be perfect. 似乎我們的計(jì)劃很完善。
17）It's my turn. 該輪到我了。
it也常用于某些習(xí)慣用語(yǔ)中作賓語(yǔ)，各該習(xí)慣用語(yǔ)有具體意義，但it并無(wú)具體意義。如：
cab it 乘車 catch it 受責(zé)，受罰 come it 盡自己分內(nèi) come it strong 做得過(guò)分 walk it 步行
make it 辦成 take it out of somebody 拿某人出氣
4. 先行詞it.
it充當(dāng)形式主語(yǔ)或形式賓語(yǔ)，本身無(wú)意義，只起一種先行引導(dǎo)的作用，先行詞不重讀。后面的真正主語(yǔ)或真正賓語(yǔ)通常是不定式結(jié)構(gòu)、-ing分詞結(jié)構(gòu)或名詞性從句。
（1）用作形式主語(yǔ)
18）It is difficult to translate this article. 翻譯這篇文章很難。
19）It is getting harder every day for a lazy man to get a living. 懶漢謀生是日益困難了。
20）What time would it be most convenient for me to call again？什么時(shí)候我再給你打電話最合適？
21）It is no use going there so early. 這么早去那里沒(méi)有用。
22）It has been a great honour your coming to visit me. 你的來(lái)訪是我很大的榮幸。
23）It is strange that he did not come at all. 真奇怪，他竟還沒(méi)來(lái)。
24）It doesn't matter what you do.什么都沒(méi)關(guān)系。
在上述諸例中，后置的真正主語(yǔ)可以取代先行it的位置，而出現(xiàn)于句首。
To translate this article is difficult.
Going there so early is no use.
That he did not come at all is strange.
上述結(jié)構(gòu)遠(yuǎn)不如用先行it結(jié)構(gòu)普通。此外，也并非所有先行it結(jié)構(gòu)都可作上述轉(zhuǎn)換。如：
25）It seems that John is not coming after all. 似乎約翰終竟不來(lái)。
26）It happened that John was the only witness. 碰巧約翰是的證人。
上述兩例只能轉(zhuǎn)換為：
John doesn't seem to be coming after all.
John happened to be the only witness.
（2）用作形式賓語(yǔ)
27）I found it difficult to explain to him what happened. 我覺(jué)得向他解釋清發(fā)生了什么事很困難。
28）He thought it no use going over the subject again. 他認(rèn)為再討論這個(gè)問(wèn)題沒(méi)有用了。
29）They kept it quiet that he was dead. 他們對(duì)他的死保密。
30）We must make it clear to the public that something should be done to stop pollution.
我們必須使公眾明白應(yīng)該采取措施制止污染。
5. 分裂句引導(dǎo)詞it.
分裂句是以it為引導(dǎo)詞的強(qiáng)調(diào)句型。它的結(jié)構(gòu)形式是：It+be的一定形式+中心成分+that-/who-從句。如：
31）It was Jane that/who called this morning. 是珍妮今天上午打來(lái)電話。
32）It was a parcel that she brought him. 她帶給他的是一個(gè)包裹。
分裂句是由普通陳述句轉(zhuǎn)換而來(lái)的。通過(guò)這種結(jié)構(gòu)可以強(qiáng)調(diào)除謂語(yǔ)動(dòng)詞以外的大多數(shù)句子成分。如：
33）John gave Mary a handbag at Christmas. 約翰在圣誕節(jié)給了瑪麗一個(gè)提包。
根據(jù)上下文和語(yǔ)義意圖，說(shuō)話人可以通過(guò)分裂句分別強(qiáng)調(diào)主語(yǔ)、間接賓語(yǔ)、直接賓語(yǔ)、狀語(yǔ)，使之成為信息中心。
34）It was John that/who gave Mary a handbag at Christmas. 是約翰在圣誕節(jié)給了瑪麗一個(gè)提包。
35）It was Mary that John gave a handbag （to） at Christmas. 約翰在圣誕節(jié)是給瑪麗提包的。
36）It was a handbag that John gave Mary at Christmas. 約翰在圣誕節(jié)給瑪麗的是一個(gè)提包。
37）It was at Christmas that John gave Mary a handbag. 是在圣誕節(jié)約翰給了瑪麗一個(gè)提包。
分裂句的時(shí)態(tài)一般應(yīng)一致，即主句與從句的時(shí)態(tài)應(yīng)皆用現(xiàn)在時(shí)，或皆用過(guò)去時(shí)，或皆用將來(lái)時(shí)。如：
38）It is not I who am angry. 發(fā)怒的不是我。
39）It was my two sisters who knew her best. 是我的兩個(gè)姐妹最了解她。
40）It will not be you who will have to take the blame for this. 對(duì)此須受責(zé)難的將不是你。
有時(shí)分裂句的謂語(yǔ)動(dòng)詞還可以采取復(fù)雜形式。如：
41）It may have been at Christmas that John gave Mary a handbag. 可能是在圣誕節(jié)約翰給瑪麗一個(gè)提包。
42）It might have been John who gave Mary a handbag. 很可能是約翰給了瑪麗一個(gè)提包。
分裂句可以強(qiáng)調(diào)多種多樣的狀語(yǔ)成分。如：
43）It was when she was about to go to bed that the telephone rang. 是在她即將上床睡覺(jué)時(shí)電話鈴響了。
44）It was because I wanted to buy a dictionary that I went to town yesterday. 我昨天是由于想買一本詞典而進(jìn)城的。
45）It was not until his father came back that Tom went to bed yesterday. 昨天湯姆是直到他父親回來(lái)才上床睡覺(jué)的。（注意句中not的位置）
主語(yǔ)補(bǔ)語(yǔ)通常不可以用作分裂句的中心成分，如在規(guī)范英語(yǔ)中通常不說(shuō)：
It is beautiful that she is.
It is chairman of the Committee that he is.