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 they offered you the job, .................................... ?

A. will you accept it

B. have you accepted it

C. would you have accepted it

D. do you think you would accept it

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: What would you do if war .......................... ?

A. break out

B. will break out

C. were to break out

D. breaks out

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: The farmers got their crops ................... earlier than they hadexpected.

A. picked 

B. has picked

C. pick

D. was picked