11. While the National Anthem ____, the audience all stood to attention.

　　A. is played B. is being played

　　C. was playing D. was being playing

　　12. A railway train cannot run ____ the track has been laid.

　　A. when B. until C. as long as D. as

　　13. The policemen went into action ___ they heard the alarm.

　　A. promptly B. presently C. quickly D. directly

　　14. ___ this is no opposition, we shall hold the meeting here.

　　A. While B. Ever since

　　C. Provided that D. As soon as

　　15. She crept in ___ she might wake up her husband.

　　A. in spite of B. so that

　　C. for fear that D. on condition that

　　16. A scientist needs imagination if he wants to make hypothesis ___.

　　A. how to do processes work and how do events take place

　　B. of processes work and events take place

　　C. of how processes work and how events take place

　　D. how processes work and how events take place

　　17. The only thing ______ really matters to the parents is how soon their children can return home.

　　A. what B. that C. which D. this

　　18.___ pollution control measures tend to be money consuming，many industries hesitate to adopt them.

　　A. Although B. However C. When D. Since

　　答案与解析

　　1.[D];

　　解析：先行词前有形容词最高级修饰，所以要用that作引导词，that可以省略。

　　2.[A];

　　解析：whoever 在宾语从句中作主语，相当于anyone who。

　　3.[A] ;

　　解析：what引导宾语从句，相当于the thing that。

　　4.[A];

　　解析：who 在定语从句中作主语，其先行词是复数名词people，所以谓语动词用复数形式。

　　5.[D] ;

　　解析：that 引导同位语从句。

　　6.[D];

　　解析：what引导主语从句，相当于the thing that，why引导表语从句。

　　7.[B];

　　解析：it为形式宾语，that从句为真正的宾语。

　　8.[C];

　　解析：so…that 引导结果状语从句。

　　9.[D];

　　解析：lest引导目的状语从句，意为“以免”。

　　10.[A];

　　解析：where 引导状语从句。