speed at instant of contacts touching

例句：

1. 1. The car accelerates to 60 miles per hour on the highway.
   汽车在高速公路上以每小时60英里的速度加速。
2. 2. The project will be completed in two months' speed.
   这个项目将在两个月内完成。
3. 3. The racers need to maintain a steady speed to avoid accidents.
   赛车手需要保持恒定的速度以避免事故。