2014年12月英语四级语法精讲：条件状语从句

　　2014年12月份的四六级备考正在紧锣密鼓的进行中，下面是2014年12月英语四级语法精讲：条件状语从句，查看更多关于四级英语语法的内容，请关注新东方在线。

　　条件状语从句：

　　(1)连接词：if, once, as long as, on condition that

　　① 如果引导的条件可以实现，主将从现;

　　② 如果引导的条件和事实相反，则用虚拟语气;

　　eg：If winter comes can spring be far behind.

　　As long as it doesn't rain, we can play.

　　You can go out on condition that you wear an overcoat.

　　Modern cars are far tougher to steal, as their engine management computer won't allow them to start unless they receive a unique ID code beamed out by the ignition (点火) key.