动词不定式的不同形式（以动词不定式的不同形式（以do为例）为例）主动主动被动被动一般式一般式 to do to be done进行式进行式 to be doing完成式完成式 to have doneto have been done完成进行式完成进行式to have been doing作主语的不定式作主语的不定式:To do is Its+adj.+to do(Its+adj for sb to do Cf Its+adj+of sb to do)Its+n+to do(Its fun/a pity/a shame/good manners/bad manners to do)Its+prep+to do(Its of use/of value/beyond me/not within my power/just like her+to do)It+V+n+to do(take/cost/require)作主语的不定式作主语的不定式:1.To tell a lie is wrong.(It is wrong to tell a lie.)2.To be invited here i
