In my opinion,Tim doesn't write English( )his sister.

In my opinion,Tim doesn't write English( )his sister.
A.as clear as B.so clear as C.more clearly as D.as clearly as
Luckily,Ben won the first prize.He doesn't usually run as( )as John.
A.fast B.quick C.slow D.fastly
答案分别是D；A,为什么前面都是动词,为什么as.as当中一个一个用副词,一个用形容词?