记住了,only if的实质就等于if,only只是修饰词.从意思上讲,only if=as long as,表示“只要”,引导的是条件状语从句.但出题目时候,only if很容易放在句首,因为only修饰了状语,所以后面要部分倒装,比如Only if you work hard can you succeed.=You can succeed only if you work hard.=You can succeed as long as you work hard. if only引导的从句,后面都是虚拟语气,有一种“如果...就好了”的感觉.