The US is a large country many different dialects are spoken.A. whatB. whenC. whereD. whi

问题补充：

The US is a large country many different dialects are spoken.

A. what

B. when

C. where

D. which

答案：

A. what

B. when

(答案→)C. where

D. which

解析：美国是多种口音并存的国家。关系副词指代country，在定语从句中作地点状语。答案为C。