有些名词单复数同形,可根据意思决定谓语动词的数:

This new series is beginning next month.

These new series are beginning next month.

This species is now extinct.

These species are now extinct.

表示时间,重量,长度,价值等的名词,尽管仍是复数形式,如果作整体看待,动词也可用单数形式(当然用复数动词也是可以的):

Three weeks was allowed for making the necessary preparations.

One hundred li was covered in a single night.

书名,国家名用单数:

Tales from Shakespeare is a book by Charles Lamb.

学科名,如mathematics,economics用单数.

many a或more than one所修饰的词作主语时,谓语动词多用单数形式:

Many a person has had that kind of experience.

More than one person has involved in the case.

a number of后接复数,the number of后接单数:

A number of books have been published on the subject.

The number of books published on the subject is simply amazing.

one of those后用单数.在“one of+复数名词+关系分句”结构中，关系分句中谓语动词的单复数形式在一般情况下有两形式，一是根据先行词采用复数形式：

Joan is one of those people who go out of their way to be helpful.

当one之前友the only等限定词和修饰语时，关系分句谓语动词根据one而定，即采用单数形式：

He is the only one of those boys who is willing to take on another assignment.

Joan is one of those people who go out of their way to be helpful.

当one之前友the only等限定词和修饰语时，关系分句谓语动词根据one而定，即采用单数形式：

He is the only one of those boys who is willing to take on another assignment.

非谓语动词

不定式

形式

主动形式被动形式

一般式to do to be done

完成式to have done to have been done

进行式to be doing

完成进行式to have been doing

完成式:不定式的一般形式所表示的动作,通常与主要谓语表示的动作(状态)同时(或几乎同时)发生,或是在它之后发生.假如不定式所表示的动作,在谓语所表示的动作(状态)之前发生,就要用不定式的完成式。

I am glad to have seen your mother(=I am glad I have seen your mother).

(比较:I am glad to see you.)

He is said to have written a new book about workers.

He pretended not to have seen me.

进行式:如果主要谓语表示的动作(状态)发生时,不定式表示的动作正在进行,这时要用不定式的进行式。

You are not supposed to be working.You haven't quite recovered yet.

We didn't expect you to be waiting for us here.