Câu hỏi: Mathematics and Literature are..............subject in high schools.

A. adding

B. compulsory

C. optional

D. religious

Câu 1: How many countries took part in the first World Cup?

A. interested

B. participated

C. competed

D. cooperated

Câu 2: UFOs mean ................flying objects.

A. unknown

B. unidentified

C. unable

D. unimaginary

Câu 3: We should........all the electric appliances when leaving our room.

A. turn of

B. turn on

C. turn up

D. turn off

Câu 4: Our actions express our love more than any words can do.

A. help

B. create 

C. make

D. show

Câu 5: Some tiny organisms are..........along by the currents.

A. carried

B. taken

C. flowed

D. beside

Câu 6: The existence of different kinds of animals and plants which make a balanced environment is called........

A. biodiversity

B. rubbish

C. challenge

D. maintain