全国大众英语测验语法——非真实前提句
1）时态：可以默示过往，现在和将来的情况。它的根基特点是时态退后。
a.同现在毕竟相反的假定。
句型：前提从句主句
普经由历程往时should( would) +动词底细
If they were here, they would help you.
b.默示于过旧毕竟相反的假定。
句型：前提从句主句
过往完成时 should(would) have+过往分词
If she had worked harder, she would have succeeded.
The rice would not have been burnt if you had been more careful.
If my lawyer had been here last Saturday, he would have prevented me from going.
If he had come yesterday, I should / would have told him about it.
含义：He did not come yesterday, so I did not tell him about it.
If he had not been ill and missed many classes, he would have made greater progress.
含义： He was ill and missed many lessons, so he did not make greater progress.
c.默示对将来的设想
句型：前提从句主句
普经由历程往时 should+动词底细
were+不定式 would +动词底细
should+动词底细
If you succeeded, everything would be all right.
If you should succeed, everything would be all right.
If you were to succeed, everything would be all right.

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