Chọn đáp án đúng: One of the major causes _________ heart disease is lack of exercise

8. One of the major causes _________ heart disease is lack of exercise.

A. for

B. to

C. of

D. by

9. On March 27, a lot of firework is _________ off in Danang city.

A. set

B. gone

C. placed

D. burned

10. He _________ an overdose of heroin and died.

A. used to

B. used

C. was used to

D. was used