if only 和only if 的区别

你好。简要地说：1 if only == how I wish - - -- ! --------- 用于虚拟语气的句子：If only she knew I need her! (but she doesn't know I need her。) If only she could have lived a little longer! (but she didn't stay long。)2 only if -------- 用于倒装句,条件状语从句：Only if I have enough time, will I go with you。 ===If I have enough time。 I will go with you。 Only if we all help, shall all be saved。 ==== If we all help, all (the animals) will be saved。