16.2 非真实条件句 1）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…...

16.9 need "不必做"和"本不该做" didn't need to do表示： 过去不必做某事, 事实上也没做。. needn't have done表示： 过去不必做某事, 但事实上做了。 John went to the station with the car to meet Mary, so she didn't need to walk back home. …...

16.4 虚拟条件句的倒装 虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略，再把were, should或had 移到从句句首，实行倒装。 Were they here now, they could help us. =If they were here now, they could help us. Had you come ea…...

19.6 条件状语从句 连接词主要有 if, unless, as/so long as, on condition that 等。. if 引导的条件句有真实条件句和非真实条件句两种。非真实条件句已在虚拟语气中阐述。 unless = if not. Let's go out for a walk unless you are too tire…...

16.6 wish的用法 1）用于wish后面的从句，表示与事实相反的情况，或表示将来不太可能实现的愿望。其宾语从句的动词形式为： 真实状况 wish后 从句动作先于主句动词动作 现在时 过去时 （be的过去式…...

16.1 真实条件句 真实条件句用于陈述语气，假设的情况可能发生，其中 if 是如果的意思。 时态关系句型： 条件从句 主句 一般现在时 shall/will + 动词原形 If he comes, he will bring his violin.典型例题 The volleyball match will be …...

16.8 It is (high) time that It is (high) time that 后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。 It is time that the children went to bed. It is high time that the children should go to bed. ...

16.3 混合条件句 主句与从句的动作发生在不同的时间，这时主，从句谓语动词的虚拟语气形式因时间不同而不同，这叫做混合条件句。 If you had asked him yesterday, you would know what to do now. （从句与过去事实相反，主句与现在事实相反。） …...

19.2 方式状语从句 方式状语从句通常由as, (just) as…so…, as if, as though引导。 1） as, (just) as…so…引导的方式状语从句通常位于主句后，但在(just) as…so…结构中位于句首，这时as从句带有比喻的含义，意思是"正如…"，"就像"，多用于正式…...

16.5 特殊的虚拟语气词：should 1） It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形， should 可省略。句型： (1)suggestedIt is (2)important that…+ (should) do (3) a pity(1)suggeste…...