of my parents used to travel all over the country on their own.A. BothB. AllC. EitherD. Ea

问题补充：

of my parents used to travel all over the country on their own.

A. Both

B. All

C. Either

D. Each

答案：

(答案→)A. Both

B. All

C. Either

D. Each

解析：词义辨析。Both两个都； All所有都；Either两个中的任何一个； Each每一个。句意：我的父母都曾经在全国各地自助旅行。结合语境可知选A.