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

A. what

B. how

C. if

D. because

Câu 1: If you’re not coming, ............................

A. we had not been in such trouble

B. you may need to tell me

C. we’d never met

D. you’d be so lucky

Câu 2: ......................... 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 3: The first hamburgers ..................... in Connecticut in 1895.

A. are sold 

B. were sold

C. sold

D. have been sold

Câu 4: If I’d known you weren’t coming, ................................

A. I had come too

B. I would like to know why

C. I wouldn’t have gone to so much trouble

D. I hadn’t been so upset

Câu 5: If it ..................... last weekend, we would have gone skiing.

A. snowed

B. would have snowed

C. had snowed

D. would snow

Câu 6: A small design fault ................. on our latest chip.

A. has found

B. found

C. has been found 

D. find