（2）连词 +现在分词

Look out while crossing the street.

（3）连词 + 形容词/其他

常见的有it necessary、if possible、when necessary、if any等。

二、精典名题导解

选择填空

1. I don’t think I’ll need any money but I’ll bring some ____________.

A.as last B.in case C.once again D.in time

解析：答案为B。句意为“带些钱以防万一”，只能选择in case。引导的条件状语从句，后面省略了I should need it。

2. The WTO can’t live up to its name _________ it doesn’t include a country that is home to one fifth of man-kind.

A.as long as B.while C.if D.even though

解析：答案为C。本题考查状语从句的用法。句意为“假如世贸组织不包括占世界人口五分之一的中国的话，那它就名不副实”。as long as语气过于强烈，while和even though不符合句意。

3、Someone called me up in the middle of the night, but they hung up_________I could answer the phone.

A.as B.since C.before D.until

解析：答案为C。题意为：半夜里有人打来电话，我没来得及就挂了。but暗示在接话前就挂了。