UNLESS 有如果不的意思吗 怎么用

unless意为“如果不”例句如下：

I shall go there tomorrow unless I'm too busy.
如果我不太忙，明天将到那儿去。

unless
[En5les, Qn5les]
conj.
如果不, 除非

举例：

如果不： unless you finish doing the homework, you are not allowed to watch the TV.
如果你不做完作业，你不许看电视。

除非：i'll go to your party unless i have to take an exam that day.

我将会去你的宴会，除非那天我要考试。

unless的意思是 除非什么 ，介词，
如：you cannot play the computer unless you have finished you homework.

Don't you tel me unless you can back!
如果你不回家，为什么不给我打电话