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

　　16.The advertisements are trying ________ people to buy things they don‘t really need.

　　A. persuade

　　B. persuading

　　C. be persuading

　　D. to persuade

　　17.Practice ________ English every day.

　　A. speak

　　B. to speak

　　C. speaks

　　D. speaking

　　18.The discount houses were first established in that period of time ________ people‘s purchasing power was low.

　　A. which

　　B. that

　　C. when

　　D. where

　　19.Please write a report ________ the above subjects are to be covered.

　　A. which

　　B. in which

　　C. that

　　D. in that

　　20.The reason ________ I‘m writing is to ask for your permission to translate your latest novel into Chinese.

　　A. because

　　B. why

　　C. for

　　D. as