英语语法中“it”的用法

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　　在英语中， it 有许多不同的用法。它既可以用作代词(如人称代词、非人称代词)，也可以用作引导词(作形式主语或形式宾语)，还可以用来构成强调句型。

　　1. it 用作人称代词，指代前面提到过的人或事物。如：

　　He bought a dictionary and gave it to me. (指代物品 dictionary )

　　John hates children， and it is difficult to say why.

　　(指代前面提到的事情)

　　2. 表示天气、时间、温度、距离等。如：

　　It was raining when I left the office.

　　(表示天气)

　　It's an hour's walk from my home to the school.

　　(表示距离)

　　It's a long time since we met last time. (表示时间)

　　3. it 用作形式主语或形式宾语

　　根据句子结构的需要，人们常用 it 作形式主语或形式宾语，而把真正的主语或宾语(不定式短语、动词- ing 形式短语或名词性从句)置于句尾。如：

　　It is important to learn English well.

　　It is a pity that I didn't think of it earlier.

　　We found it strange that no one would take the money.

　　4. it 用在强调句型中

　　英语中，有时为了突出句子中的某一成分，达到强调或使人特别注意该成分的目的，人们常用“ It is / was … that/ who …”句型把整个句子分割成前后两个部分，使之各自有自己的谓语动词，中间由 that 或 who 连接起来成为一个新的句子，人们习惯上称这一句型为强调句型。如：

　　Mathilde wore the beautiful diamond necklace to attend the palace ball with her husband last night.

　　→ It was Mathilde who wore the beautiful diamond necklace to attend the palace ball with her husband last night. (强调主语)

　　→ It was the beautiful diamond necklace that Mathilde wore to attend the palace ball with her husband last night. (强调宾语)

　　→ It was with her husband that Mathilde wore the beautiful diamond necklace to attend the palace ball last night. (强调方式状语)

　　→ It was last night that Mathilde wore the beautiful diamond necklace to attend the palace ball with her husband. (强调时间状语)

　　另外，学习 it 的用法时，还要注意学会使用下列常用句式：

　　It takes / took / will take sb some time to do sth

　　做某事花费某人多少时间

　　It looks / looked as if …看起来好像……

　　It seems / seemed that …似乎……

　　It so happened that …碰巧……

　　It turns / turned out that …原来是(结果是)……

　　It is said / reported / believed / thought / hoped / well-known / suggested that …据说 / 报道 / 相信 / 认为 / 希望 / 众所周知 / 建议……

　　It occurred to sb that …某人想起……

　　It will be / was + some time before …要过多久才 / 过了多久才……

　　It is / was / has been / had been + some time + since …自从……已经有多久时间了……