谁能告诉我IF引导的条件状语从句

语法引导条件状语从句最常用的连词是if,由if引导的条件状语从句表示在某种条件下某事很可能发生。如:If you ask him,he will help you。如果你请他帮忙,他会帮你的。If you fail in the exam,you will let him down。如果你考试不及格,你会让他失望的。另外,if从句还表示不可实现的条件或根本不可能存在的条件,也就是一种虚拟的条件或假设,从句多用一般过去时或过去完成时。如:If I were you,I would invite him to the party。如果我是你,我会邀请他参加聚会。I would have arrived much earlier if I had not been caught in the traffic。如果没有堵车,我会到的早一点儿。