Câu hỏi: The problem of_______ in big cities, which stems from uncontrolled migration from rural areas.

A. overpopulation

B. decrease

C. increase

D. growth

Câu 1: The factory was fined for______ chemicals into the river.

A. dumping

B. discharging

C. producing

D. exposing

Câu 2: The waste water from bath, showers, sinks and_______, and rainwater can be collected in a tank.

A. linguistic

B. official

C. dishwasher

D. operate

Câu 3: He had a new heart valve _______.

A. added

B. supplanted

C. improved

D. implanted

Câu 4: I_______ George on my way home.

A. dropped in on

B. gear up for

C. pair up with

D. look back on

Câu 5: The _______ by UN troops prevented fighting from breaking out.

A. participant

B. intervention

C. joiner

D. contestant

Câu 6: This_______disease caused a lot of complications during the treatment procedure.

A. situation

B. difficult

C. life-threatening

D. weak