题目

如图，黑龙江省冬季下大雪时，汽车在公路上紧急刹车总是要滑行一段距离才能停下来，这是由于与的原因． 答案：【1】汽车具有惯性【2】车胎与地面之间的摩擦力变小（减小） It was not until ________ that ________ to study English well． [　　] A．he came to Beijing; did he begin B．did he comet to Beijing; he began C．he came to Beijing ; he began D．did he come to Beijing; did he begin