Travelling west, you set your clock ______; travelling east, you set it ahead.

1. A.
   behind
2. B.
   forward
3. C.
   back
4. D.
   ahead

Travelling west, you set your clock ____; travelling east, you set it ahead.
A. behind     B. forward     C. back     D. ahead

Travelling west, you set your clock ______; travelling east, you set it ahead.

Travelling west, you set your clock ______; travelling east, you set it ahead.

A．behind           B．forward           C．back             D．ahead