need的过去式「need和must的过去式」

t含有情态动词的谓语变成被动语态时，结构为：

t一般式：情态动词（can,could,may,might,must,should,need等）+be+过去分词

t完成式：情态动词（can,could,may,might,must,should,need等）+have+been+过去分词

t例句：

tLost health may be replaced by temperance or medicine.

t失去的健康可以靠节制或药物而复得。

tThis can be done by hand.

t这可以手工做。

tThis mustnt be neglected.

t这一点不可忽视。

tIt neednt be mentioned in your talk.

t这一点你在谈话中不必提及。

tThe environment should be improved.

t环境应当改善。

tThe project might have been completed earlier.

t这项工程本可以早点完工的。

tSuch a situation could have been changed.

t这种情况本可以改变的。

tThey shouldnt have been told about the plan.

t这个计划是不应当告诉他们的。