Question

        is a bad habit. People should give it up.
A. Smoke                    B. To smoke            C. Smoking

Answer 1

C

试题分析：句意:抽烟是一个坏习惯。人们应该放弃。本句中is前面缺少主语，所以应该用动名词作主语，即smoke的ing式。故选C。