Câu hỏi: ......................... any difficulty operating the machine, do not hesitate totelephone our service department.

A. Should you have

B. If you should

C. In case you have

D. Unless you have

Câu 1: Exactly .............. we can replace our soil disappearing through erosion is not known.

A. what

B. how

C. if

D. because

Câu 2: The hurricane was so strong that it damaged the whole area ........................ itwas approaching or receding.

A. whether

B. and if

C. but

D. because

Câu 3: Their popularity ................ much more after the Second WorldWar.

A. grew

B. grow

C. is grown

D. has grown

Câu 4: Hamburgers ...................... favorite in America in the early century.

A. became

B. becomes

C. has become

D. was become

Câu 5: If you’re too ill to come,     ......................................

A. I’ll come over and see you

B. I wouldn’t have done all this for you

C. I asked someone else

D. I’d have come to see you

Câu 6: We’ll have to break the ice on the pond; otherwise the ducks .............. swim.

A. are not able to

B. will not be able to

C. would not be able to

D. would not have been able to