名词，代词或其他结构作主语时，谓语动词在人称和数上必须与主语保持一致。
1、主语是可数名词单数时，谓语动词用单数形式
主语是复数时，谓语动词用复数形式，
eg*All roads lead to Rome (条条大路通罗马）
·His brother is an industrial engineer、
·The number of the students attendling the party is increasing
*the number of“..的数量”无论后面单数复数谓语动词是单数形式
·Both of us are studying Engbsh
2、主语是不可数名词，不定式或动名词词组，从句时，谓语动词用单数形式。
All the money he received was given to his mother
Forgetting the past means betrayal
what we are talking now is unless
3、主语部分若有 as wel as,with,together with,like,but,except等短语，谓语动词的单，复数与短语前面的名词一致。
4、表示时间，距离，重量，价值等的复数名词作主语时，如果当作整体看待，谓语动词用单数形式。
“。。。＋（x)···=....”算式中的谓语动词也用
单数形式。
·Three times two is six
·Three hilorneters is 3000 meeters
▲情态动词部分除了应了解每个词的具体含义之外，否定为后加not
had better→had better not
would rather→would rather not
*ought to 的否定为ought not to
*would rather +句子(一般过去时)
*can，could,may,might,must,ought to,should后接动词完成式，表示 对过去事情的猜测
*may/might have done 也许已经....了
must have done 肯定...了(对过去的猜测)
can/could have done 本来是能够...的(实际上未)
shoud/ought to+have done 本应该...(实际上未)
▲有些情态动词，如can,could,may,might,must
ought to,should. 后面可以接动词的完成式
表示对已经发生的事的猜测或对应该发生的事的看法。
·They shouldn′t have left so soon,他们本不该那么快离开
They must have been out last night
他们昨晚应该不在家（对过去事实的猜测）
·I meedn′t hove told them that 我本不必告诉他们那些
·He can′t have left for shanghai for I saw him a moment aga.
他可能还没有离开去上海因为我刚看到他
you ought n′t to have done that
你本不应该那样做
8、would rather 表示“宁愿”后接从句时，从句谓语用一般过去时、
否定为 would rather not
eg: I′d rather not say anything
I would rather you come tomorrow
7、had better 表示“最好”
否定为 had better not
I had better not disturb him 我最好不要打扰他
6.none 代表可数的人或东西时、谓语动词可以用单数也可以用复数，代表不可数的东西时，谓语动词用单数形式，
None of the students have/has seen the film
None of the money belongs to me
5、either(两者中一个）neither(三者中任何一个都不）
谓语动词用单数形式，
Neither of us has been to Italy
Has either of them been to shanghai?
