五、unless引导的状语从句

unless的意思是“如果不……”“除非”，对于涉及unless的考题，一般只要能读懂句意，弄清语境，一般不会有问题。如：

1. Most birds find it safe to sleep in the trees, but ______ they have eggs or young chicks, they don’t use a nest. (湖南卷)

A. why B. how C. unless D. where

2. I won’t call you, ______ something unexpected happens. (全国I)

A. unless B. whether C. because D. while

【解析】两道题都选unless，均表示“除非”。

六、until引导的状语从句

until的意思是“直到……时”“在……之前”，对于涉及until的考题，一般只要能读懂句意，弄清语境，一般不会有问题。如：

It is difficult for us to learn a lesson in life ___A___ we’ve actually had that lesson. (天津卷)

A. until B. after C. since D. when

另外，还要注意not…until…这一句式(直到……才)。如：江苏高考网

“You can’t have this football back ___D___ you promise not to kick it at my cat again,” the old man said firmly. (广东卷)

A. because B. since C. when D. until