急求各种被动语态例句一般过去时的被动语态例句 一般将来时的被动语态例句 过去将来时的被动语态 现在进行时的被动语态 现在

过去 Had done Would* have done
现在 Were/did Would* do
将来 Should do/were/were to do Would* do
例句：If there hadn’t been much rain in spring,we would have had a good harvest now.[过去]
If he smoked less,his cough might be well soon.[现在]
If the lecturer should be late,you would have to make a speech first.[将来]
主动:We must keep this in mind.
被动：This must be kept in mind.
我们必须把这个记在心里.

被动语态分四类，（8种时态，含情态动词的，(to)动词不定式，长宾语的）
例：You must cook supper this evening.
Supper must be cooken this evening.
This factory produces machine tools.
Machine tools are produced in this factory.
.
.
.