如题所述
1、表示与现在事实相反的,if从句用过去式,主句用would (或could、should、might)加原形动词。
2、与将来事实可能相反的,if 从句用should (或were to )加动词原形,主句用would加动词原形。
在笔语中,条件从句有时可以不用连词小而把were,had或should移至主语之前。但如从句没有were,had或should,则一般不能这样做
如:Should he come,tell him to ring me up.
他要是来了,让他给我打个电话。
If I were you, I would helphim. (对现在的虚拟,假如我是你)
If it were to rain tomorrow, Iwould not go hiking. (对将来的虚拟)
扩展资料
其他用法:
有时条件从句中的动作和结果主句中的动作所发生的时间不一致
1、这时,动词的形式应根据它所表示的时间加以调整。
如:If he had followed the doctor's advice,he Would be quite all right now.
他当时若是听医生的话,现在就会痊愈了。
从句说明过去,主句说明现在
If I were you,I Would have gone to the theatre.
假如我是你,我会去看话剧了。
从句的时间包括现在,主句说明过去
If you hadn't helped me,I couldn't have finished it on time and most likely I would be still working now.
假若你没有帮助我,我不可能按时完成工作,很可能现在还在干哩。
2、用直陈语气表示条件和结果
在现代英语里,多用直陈语气表示条件和结果。直陈语气的条件和结果所表示的往往是事实。如不是事实,其可能性也较虚拟语气要大。
如:If it rains tomorrow,we shall not go out.
假如明天下雨的话,我们就不出去。
The dog won't attack you if you sit still.
如果你安静地坐着,狗是不会咬你的。
与现在事实相反:从句动词用:did/were; 主句动词用:would do/ be
与将来事实相反:从句动词用:should(were to) do /be 主句动词用:would do/ be
用在以if引导的非真实条件状语从句中,从句和主句皆须用虚拟语气。从句和主句动词的搭配形式,通常为:
与现在事实相反:从句动词用:did/were; 主句动词用:would do/ be
与过去事实相反:从句动词用:had done/been 主句动词用:would have done/ been
与将来事实相反:从句动词用:should(were to) do /be 主句动词用:would do/ be
三种基本形态(这是基础,建议牢记下面的例句,争取能脱口而出)
与现在事实相反:If I had enough money, I would buy a book.
与过去事实相反:If I had had enough money, I would have bought a book.
与将来事实相反:If I were to have enough money, I would buy a book.
If I should have enough money, I would buy a book.本回答被提问者采纳