问题
选择题
He knows it is high time that he ________ at once.
A．quits smoking
B．quitted smoking
C．should quit to smoke
D．quitted to smoke
答案
答案：B
本题考查虚拟语气及动词用法。it is high time that + 主语 + 过去时态/should + v原形；quit doing 放弃做。故选B。