原因状语从句:常由because, as, since和for引导。例如:Nonetheless, I am still in favor of space travel, for it has brought us many benefits. 时间状语从句:常由when和while引导。...
常搭配的时间状语:by then, until then,by that time, before 2000, by the end of last month, by the time he was ten,… 过去完成时的用法: 1.过去的过去;到过去某个时间为止的动作 2.hardly/scarely(过完)… when(一般过去) no sooner(过完)… than(一般过去) 表...
when可作并列连词,常用于引导一个突然出现的动作,意为“那时/这时……”,此时句子的形式如下:1.Somebody was doing something when…; 2.Somebody was about/ going to do something when…; 3.Somebody was on the point of doing something when…; 4.Somebody had ...
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