卫生类职称英语考试语法：

“It”的用法

1.代词it

（1）指除人以外的一切生物和事物。如：

I hope it was as good as the one you lent me.

I knew at once that it was a gift from Father.

The more carbon the steel contains, the harder it is.

（2）在某种情况下代词it也可以指人。这时可把it看作指示代词。如：

Is it your brother?

I didn't know it was you.

"Oh? who was it?" Mr.Black asked.

（3）it用来表示自然现象、时间、距离等。如：

It is nine sharp now.

It is very hot today.

It is far to the airport.

2.it 作形式主语

（1）做不定式的形式主语

It's nice to be with you.

It's not easy to get him to change his mind.

Is it possible to go by bike?

（2） that…句的形式主语

It's true that she's ill.

It seems obvious that we can't go on like this.

It occurred to me that she might have forgotten the date.

It doesn't interest me whether you win or not.

It doesn't matter when you arrive — just come.

It wasn't very clear what she meant.

It's surprising how many unhappy marriages there are.

（3）作动名词的形式主语

It was nice seeing you.

It's unusual her going off like that.

It's no use trying to explain—I'm not interested.

3.it作形式宾语

如果一个带有宾语补足语的动词不定式做宾语或一个宾语从句太长，可以用it作该不定式或宾语从句的先行词——形式宾语。如：

George made it clear that he disagreed.

She thinks it easy to understand a letter written in English.

She found it difficult to get along with him.

He felt it his duty to help her.

4.用于强调结构中的it

这种结构的句型是：It + is（was） + 被强调的部分 + that（或who）+ 其他部分。如：

It is the force of gravity that makes heavy things fall toward the ground.

It is from the sun that we get light and heat.