Question

I won’t call you, __________ something unexpected happens

1. A.
   unless
2. B.
   whether
3. C.
   because
4. D.
   while

Answer 1

A
unless的意思是“除非”，又如：Don’t call me unless you need help. 除非你需要帮助否则别打电话找我。Unless you change your mind, I won’t be able to help you. 除非你改变你的想法，否则我不能帮助你。