常见的条件状语从句引导词有“if如果”“unless除非”。
1、if 如果
We will not go out if it snows.
如果下雪，我们就不出去。
If you don't believe me， I won't believe you.
如果你不信我，我也不信你。
If you don't try， you won't get the job.
如果你不尝试，你会得不到这份工作的。
2、unless 除非 =
You won't get the job unless you try.
你将得不到这份工作，除非你尝试。
= You won’t get the job if you don't try.
= If you don't try， you won't get the job.
You won't pass the test unless you study hard.
你将无法通过考试，除非你努力学习。
= You won't pass the test if you don't study hard.
