请多看一些例句,相信你就会明白的。
unless conj。 除非;如果不; 要是不
My baby sister never cries unless she is hungry。
我刚出生的妹妹除非饿了,她是从来不哭的。
(My baby sister will cry when/if she is hungry。 )
(If she is not hungry, my baby sister will never cry。
)
I shall go there tomorrow unless I'm too busy。
如果我不太忙,明天将到那儿去。
(I shall not go there tomorrow if I am too busy。
)
(I shall go there tomorrow if I am not too busy。)
Unless you go at once you will be late。
如果你不马上走,就会迟到的。
(If you go at once, you will not be late。 )
(If you don't go at once, you will be late。
)
Unless he studies hard, he will never pass the examination。
他如果不努力学习, 就永远不能考及格。
(If he studies hard, he will pass the examination。
)
(If he doesn't study hard, he will never pass the examination。)
I shall go unless it rains。
如果不下雨我就去。
(I shall not go if it rains。)
(I shall go if it doesn't rain。)。