If you are traveling the customs are really foreign to your own please do as the Romans d

问题补充：

If you are traveling the customs are really foreign to your own，please do as the Romans do.

A. in which

B. what

C. when

D. where

答案：

A. in which

B. what

C. when

(答案→)D. where

解析：where引导修饰谓语are traveling的地点状语从句。