我们都知道，在大学英语四级考试中，单独考察英语四级语法的题型很少，但是英语四级语法知识点却贯穿整张试卷，下面是新东方网英语四级频道为大家整理的大学英语四级语法知识，希望可以为大家带来帮助。

　　2017年12月大学英语四级语法大全目录

　　16.2 非真实条件句

　　时态：可以表示过去，现在和将来的情况。它的基本特点是时态退后。

　　a.　 同现在事实相反的假设。

　　句型 ： 条件从句　　　　　主句

　　一般过去时　　　should( would) +动词原形

　　If they were here, they would help you.

　　b.　 表示于过去事实相反的假设。

　　句型： 条件从句　　　　　 主句

　　过去完成时　　　 should(would) have+ 过去分词

　　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.　 表示对将来的假想

　　句型：　 条件从句　　　　　　 主句

　　一般过去时　　　　　 should+ 动词原形

　　were+ 不定式　　　　 would + 动词原形

　　should+ 动词原形

　　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.

　　2017年12月大学英语四级语法大全目录