五、unless引導的狀語從句
unless的意思是“如果不……”“除非”，對于涉及unless的考題，一般只要能讀懂句意，弄清語境，一般不會有問題。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. (全國I)
A. unless B. whether C. because D. while
【解析】兩道題都選unless，均表示“除非”。

六、until引導的狀語從句
until的意思是“直到……時”“在……之前”，對于涉及until的考題，一般只要能讀懂句意，弄清語境，一般不會有問題。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，還要注意not...until...這一句式（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. (廣東卷)
A. because B. since C. when D. until

七、once引導的狀語從句
once的意思是“一旦”，對于涉及once的考題，一般只要能讀懂句意，弄清語境，一般不會有問題。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 (生態系統) to recover. (江蘇卷)
A. Even if B. If only C. While D. Once
【解析】兩道題都選once，均表示“一旦”。

八、where引導的狀語從句
where可以用于引導地點狀語從句，其意為“在……的地方”，此用法許多同學都不是熟悉，但高考經常考查，應引起特別注意。如：
1. If you are traveling ______ the customs are really foreign to your own, please do as the Romans do. (天津卷)
A. in which B. what C. when D. where
2. —Mom, what did your doctor say?
—He advised me to live ______ the air is fresher. (四川卷)
A. in where B. in which C. the place where D. where
【解析】兩道題都選where，均表示“在……的地方”。