三种基本形式 If had a bike,I would lend it to you(从句用过去时,主句用 should Woud/ could/ might不定式) If he had been here he would have helped you(从句过去完成时,主句 should would could/ might+不定式完成时) If I should/were to do the experiment, I would do it some other way(从句用 should/ were to,主句用 should/ would could /might不定式) 20211/21212021/2/21 三种基本形式 If I had a bike, I would lend it to you.(if从句用过去时, 主句用should/ would/ could/ might+不定式) If he had been here, he would have helped you.(从句过去完成时, 主句should /would/ could/ might +不定式完成时) If I should/were to do the experiment, I would do it some other way. (从句用 should/ were to, 主句用should/would /could /might+不定式)