if you don't know the way to the hospital,you may ask.___

if you don't know the way to the hospital,you may ask.___
A a police
B the policeman
C a policeman
D the police答案是C
2.I like a house with a garden more than _with swimming-pool.
A.one
B.the one
C.that
D.it 答案是A
2.Life in the country is quite different from __in the city.
A.one
B.the one
C.that
D.which答案是C
请问是为什么呢?