题干
What were you doing ________ the teacher came in?
A：where
B：until
C：while
D：when
答案(点此获取答案解析）
D
What were you doing ________ the teacher came in?
A：where
B：until
C：while
D：when
的速度沿平直路面行驶，当汽车以5
的加速度刹车时，则刹车2
内与刹车6
内的位移之比为 （ ）
