If you hear the fire bell, _____ cool and don’t panic.
A. keep B. to keep C. keeping D. kept
If you hear the fire bell, _____ cool and don’t panic.
A. keep B. to keep C. keeping D. kept
A
if引导的是条件状语从句，填空句为主句，而此主句为一祈使句，故动词用原形。