柠檬脾气4.即时动词不用完成时态：begin，discovery
5.一个句子中的不同动词时态。若在一个句子里，两个动词的时态一样，代表两个动
作是平行的，同样重要的。若一个句子里两个时态不一样，则时态近的是主句，另
一个动作通常代表一个背景介绍。
e.g.: She WAS PLAYING with her friends when the babysitter ARRIVED.
6.动词的时态上不能有间隔，只有相邻的时态才能出现在一个句子中
7.by the time… “到…为之” 从句一般过去时，主句过去完成时 ex. by the time I got to the station, the train had already gone.
by the time “当…的时候” 句子一般过去时
by+将来时间，主句用一般将来时或者将来完成时 例句
by+过去时间，主句用过去完成时
动词语态 主动/被动
一、重要考点
by后面一般跟动作的执行者且一定是被动语态； through 和because of 后面跟一些设备手段或者方法
只有及物动词才能用被动语态
主动语态可以和被动语态平行*
二、不能用被动语态的动词
lead; cause; enable; become; receive; visit; Lack; enter; cost; possess; resemble; last; like; enjoy; notice; watch; look at; listen to; pay attention to; suit; fit; contain; so as to do; be able to do; be likely to do
三、主动形式表达被动含义
read like…/well, prove helpful, sell well (sth be sold for+price),
be worth doing, require doing
动词语气 陈述语气，虚拟语气
一、if（as if/though）条件从句
时间
将来 从句谓语形式 动词过去式(be用were)
should + 动词原形
were to + 动词原形
现在
过去 动词过去式(be 用 were) had +动词过去分词 would / should / might / could + 动词原形 would / should / might / could 主句谓语形式 would / should / might / could + 动词原形
