I think you have to stop . It’s bad for your health.A. smokeB. smokedC. smokingD. to smoke

问题补充：

I think you have to stop . It’s bad for your health.

A. smoke

B. smoked

C. smoking

D. to smoke

答案：

A. smoke

B. smoked

(答案→)C. smoking

D. to smoke

解析：句意：我认为你必须停止吸烟了。这对你的健康有害。Stop后接动名词表示停止正在做的动作，接不定式表示停下来去做另一个动作，结合语境可知选C。