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

A. what

B. how

C. if

D. because

Câu 1: The first hamburgers ..................... in Connecticut in 1895.

A. are sold 

B. were sold

C. sold

D. have been sold

Câu 2: If you'd told me you were coming, .............................

A. I can get some food in

B. I’d have found us something to eat

C. I made a lovely dish

D. I’ll buy some more food

Câu 3: If it ............................... his wife’s money, he’d never be a director.

A. was

B. isn’t 

C. had had

D. were not for

Câu 4: Take John's address with you, ................... you have time to see him whenyou’re in London.

A. if

B. unless

C. in case

D. so long as

Câu 5: ......................... 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 6: 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