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：

“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

七、once引导的状语从句

once的意思是“一旦”，对于涉及once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. You will be successful in the interview ______ you have confidence. (福建卷)

A. before B. once C. until D. though

2. ______ environmental damage is done, it takes many years for the ecosystem (生态系统) to recover. (江苏卷)

A. Even if B. If only C. While D. Once

【解析】两道题都选once，均表示“一旦”。