It is ________ understood that his carelessness caused the accident.

It is ________ understood that his carelessness caused the accident.

A.nicely well

B.beautifully well

C.pretty well

D.pretty good

答案及解析： C

解析：

题意：人们都知道是他的粗心引起了事故。pretty用作副词，修饰well. be pretty well understood理解得很透彻。