unless是从属连词,引导条件状语从句,含有否定意义,相当于if条件状语从句的否定形式.所以unless = if not.注意：unless引导的条件状语从句和if条件状语从句,与其它时间状语从句一样,用一般现在时代替将来时.
1.Unless you take more care,you’ll have an accident.
(如果不多加小心的话,你会出事故的.)
2.My baby sister never cries unless she is hungry.
(我那刚出生的妹妹除非饿了,否则她是从来不哭的.)
3.Unless bad weather stops me,I jog every day.
(除非坏天气阻拦我,否则每天我都慢跑的.)
注意 if...not=unless!会一直考在改句中
