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 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 2: If you ................... a pet bird, you’ll have to buy a cage, too.

A. buy

B. will buy

C. bought

D. had bought

Câu 3: Peasants spend most of their time on the ground, ...................... many speciesstay in trees at night.

A. if

B. though

C. because

D. as well as

Câu 4: 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 5: If it ..................... last weekend, we would have gone skiing.

A. snowed

B. would have snowed

C. had snowed

D. would snow

Câu 6: The hurricane was so strong that it damaged the whole area ........................ itwas approaching or receding.

A. whether

B. and if

C. but

D. because