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

A. situation

B. difficult

C. life-threatening

D. weak

Câu 1: He had a new heart valve _______.

A. added

B. supplanted

C. improved

D. implanted

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

A. overpopulation

B. decrease

C. increase

D. growth

Câu 4: The society was set up to______ endangered species from extinction.

A. prevent

B. distinguish

C. preserve

D. survive

Câu 5: We all regard pollution as a.......... matter to human beings.

A. solemn 

B. great

C. serious 

D. huge

Câu 6: She finally achieved her_______ of visiting the USA.

A. target

B. objective

C. desires

D. ambition