[例1]Roses need special care______they can live through winter.

A.because　B.so that　C.even if　D.as

【解析】答案B。so that引导目的状语从句，“为了”。

[例2]______you call me to say you’re not coming，I’ll see you at the theatre.

A.Though　B.Whether　C.Until　D.Unless

【解析】答案D。unless引导条件状语从句，表示“除非，如果不”。

[例3]Several weeks had gone by ______I realized the painting was missing.

A.as　B.before　C.since　D.when

【解析】答案B。before这里表示“过了……（时间）才”，引导时间状语从句。

[例4]I do every single bit of housework______my husband Bob just does the dishes now and then.

A.since　B.while　C.when　D.as

【解析】答案B。while表示前后对比，“然而，可是”。

[例5]Jasmine was holidaying with her family in a wildlife park______she was bitten on the leg by a lion.

A.when　B.while　C.since　D.once

【解析】答案A。when是等立连词，表示“正在这时”。

[例6]Parents should take seriously their children’s requests for sunglasses______eye protection is necessary in sunny weather.

A.because　B.through　C.unless　D.if

【解析】答案A。because引导原因状语从句。

[例7]It was evening______we reached the little town of Winchester.

A.that　B.until　C.since　D.before

【解析】答案D。before引导时间状语从句，表示“在……之前”。

[例8]You can eat food free in my restaurant______you like.

A.whenever　B.wherever　C.whatever　D.however

【解析】答案A。whenever引导让步状语从句，意为“无论何时”。

[例9]It was______back home after the experiment.

A.not until midnight did he go

B.until midnight that he didn’t go

C.not until midnight that he went

D.until midnight when he didn’t go

【解析】答案C。这是“It was not until…that…”引起的强调句型。

[例10]You should try to get a good night’s sleep______much work you have to do.

A.however　B.no matter　C.although　D.whatever

【解析】答案A。however引导让步状语从句，相当于no matter how。

[例11]We were told that we should follow the main road______we reached the central railway station.

A.whenever　B.until　C.while　D.wherever

【解析】答案B。until这里表示“直到……才”，引导时间状语从句。

[例12]Scientists say it may be five or six years______it is possible to test this medicine on human patients.

A.since　B.after　C.before　D.when

【解析】答案C。before引导时间状语从句，表示“过了……就”。

[例13]______I can see，there is only one possible way to keep away from the danger.

A.As long as　B.As far as　C.Just as　D.Even if

【解析】答案B。as far as I can see就我所看到的而言。as long as 只要……就，even if即使。

[例14]______，I have to put it away and focus my attention on study this week.

A.However the story is amusing　B.No matter amusing the story is

C.However amusing the story is　D.No matter how the story is amusing

【解析】答案C。However引导让步状语从句，后边必须紧跟一个形容词或副词。