—Whatareyoudoing,John?Whystop?—Tobeonthesafeside,we'dfi...

问题详情：

— What are you doing, John? Why stop?

— To be on the safe side, we'd fill up the tank now for we _______run out of gas on the way

   A. must        B. will        C. might        D. should

【回答】

C

知识点：情态动词

题型：选择题