题目

  16  Safety in the highway is not something that is totally out of our control. Here are four ways we can protect ourselves when we travel.    17    People in small cars are injured more often and more severely than people traveling in large cars. Factories of small cars are strengthening their products’ safety, which helps. But the mix of large cars and small cars on the road is the main reason of the problem. Being thrown into glass and metal car parts, or being thrown from the car can really hurt or even kill you.    18   The safety belt’s main purpose is to pull yo下列说法中正确的是: A．速度、速率和加速度的运算都遵守平行四边形法则 B．如图所示是高速公路指示牌，牌中“25 km”是指从此处到下一个出 口的位移是25km C．蹦床运动员在空中上升和下落过程中都处于失重状态 D．后人为了纪念牛顿，把N作为力学中的基本单位