ａ、ｂ两物体同时、同地、同向做匀变速直线运动，若加速度相同，初速度

不同，则在运动过程中，下列说法正确的是　　                 

A．ａ、ｂ两物体速度之差保持不变

B．ａ、ｂ两物体速度之差与时间成正比

C．ａ、ｂ两物体位移之差与时间成正比

D．ａ、ｂ两物体位移之差与时间平方成正比

短文改错 （共10小题，每小题1.5分，满分15分）

My summer travel started terribly. I was at the Shanghai Railway Station buy a ticket to Hangzhou. I was going to visit a friend here and after that I would go to Xiamen for long holiday. I bought my ticket but turned around to pick up my bag form the floor and then I realized that someone had stolen it. Luckily I had all my money on my pocket, but the only clothes I had was those I had on. It felt very strange to travel without any luggages. When I finally arrived at my friend he lent to me lots of clothes. I feel very happy that I could change my clothes at last.