If 从句主句did (were)would(could/shouldmight)do过去had donewould()have done将来didwere to doshould dowould()do* if从句里有had, should, were, 可省略if, 把had, should, were 提到句首* 用with, without, but for(要不是)， undercondition(在条件下)，but, otherwise, or代替if从句* 错综条件句*注意区分真实条件句常见引导词：if, unless, so/as long as, in case(that), on condition that, suppose(that), supposing(that), provided(that), providing(that)一、if条件句二、if only, wish, as though(if)wish/if only(如果就好了)
