题型:问答题 — Excuse me,can you tell me where the nearest bank is,please? — Oh yes! It's past the post office,next to a big market. [ ]A. Mm, let me think. B. Oh. I beg your pardon? C. You are welcome. D. What do you mean? 查看答案
题型:问答题 A,B两列火车,在同一轨道上同向行驶,A车在前,其速度vA=15m/s,B车速度vB=30m/s.因大雾能见度很低,B车在距A车400m时才发现前方有A车,这时B车立即刹车,但B车要经过1800m才能够停止.问:(1)A车若按原速前进,两车是否会相撞?若会相撞,将在何时何地?(2)若B车在刹车的同时,A车司机开始加速前进,则A车的加速度至少多大才能避免相撞事故? 查看答案