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

A. what

B. how

C. if

D. because

Câu 1: Send my regards to Lawrence ............................ you see him.

A. if

B. in case

C. whether

D. provided

Câu 2: 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 3: Be careful about the time. If you .................. too long on the first question,you ............... enough time to do the others properly.

A. had spent - would not have

B. had spent – would not have had

C. spend - will not have

D. spent - would not have had

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

A. became

B. becomes

C. has become

D. was become

Câu 5: The farmers got their crops ................... earlier than they hadexpected.

A. picked 

B. has picked

C. pick

D. was picked

Câu 6: If you ................... a pet bird, you’ll have to buy a cage, too.

A. buy

B. will buy

C. bought

D. had bought