Travelling west, you set your clock ; travelling east, you set it ahead.
A. behind
B. forward
C. back
D. ahead
网友回答
A. behind
B. forward
(答案→)C. back
D. ahead
解析：从句式来看Travelling west及 travelling east, you set it ahead.可知两者相反，ahead向前，back向后，behind在…的后面，forward向前的；结合句意：到西方旅行，你应该将你的钟往回调；到东方旅行，你要将你的钟向前调。故选C.