Câu hỏi: Although most species of small birds gather in groups at feeders provided by bird-watchers, the bright red cardinals usually appears alone or with its mate.

A. at

B. cardinals

C. or

D. its

Câu 1: My elder sisters, both of them were doctors, said they were too busy to pick me up.

A. elder

B. both of them

C. too busy 

D. to pick

Câu 2: Having finished his tem paper before the deadline, it was delivered to professor before the class.

A. having finished

B. before

C. it was delivered

D. before

Câu 3: Tenant farmers are those they either rent a farm and work it for themselves or work the farm for the owner and receive payment.

A. they

B. it

C. or

D. the owner

Câu 4: My teacher is very strict and he always makes us to finish all the exercises before leaving school.

A. is

B. strict

C. to finish

D. leaving school

Câu 5: Proteins are made up of folded irregularly chains, the links of which are amino acids.

A. made up of

B. folded irregularly

C. the links

D. which

Câu 6: Could you tell me how can I get to the city library, please?

A. Could

B. me

C. how can I

D. the