VI. There is one mistake in each sentence. Find the mistake and write your choice (A,B,C or D) . (10 pts)

___(1)___ The water and land around the chemical factory are serious polluted.
A B C D
___(2)___ They asked me what did happen last night, but I was unable to tell them.
A B C D
___(3)___ One of the most urgent problem facing us now is the need to control population growth.
A B C D
___(4)___ The harder you learn, the most knowledge you get.
A B C D
___(5)___ It takes Hoa two hours doing the homework every day.
A B C D