11.He was busily engaged ______ writing letters.
A. on B. in C. with D. by
12.Do remember to ______ the light when you leave the room.
A. turn up B. turn on C. turn off D. turn down
13.The atmosphere consists of an ocean of gases ______ miles high.
A. hundreds B. hundreds of C. of hundreds D. of hundreds of
14.Not only the students but also the old teacher ______ been changed.
A. was B. were C. has D. have
15.—— ________ I had!
—— You really suffered a lot.
A. What a time B. What time C. How a time D. how time
答案：
11.正确答案：B答案解析：be engaged in：从事，忙于。
12.正确答案：C答案解析：根据句意，应该选择“关闭”。句意：离开房间时一定记着把灯关掉。
13.正确答案：B答案解析：译文：大气由上百英里高的气体组成。“hundred，thousand等数词的复数形式+of短语”表示的是不确切的数量。
14.正确答案：C答案解析：not only…but also…是固定搭配，意思是：不但……而且……。它需要遵循就近原则，谓语动词应与the old teacher一致，所以答案是C.
15.正确答案：A答案解析：感叹句分两类：
1：What + n.+主谓部分2：How + adj. / adv. / v.+主谓部分。本题属第一种，但省略了bad，相当于 What a bad time I had! 这是个习惯用语。
