Some people don't believe that driving more slowly can save lives．But the truth is that driving more slowly can help a person to avoid serious accidents．

The above chart（表格） shows the distance that it takes to stop a car at a given speed．The distance is measured in feet．The shaded area（阴影部分） shows the driver's thinking distance．That's the distance it takes for the driver to react to a danger that he sees．The white area shows the car's braking distance．That's the distance it takes for the car to stop once the brakes（闸、刹车） are used．The number at the top of each bar shows the total number of feet that it takes to stop the car

小题1:According to the chart, what is the total number of feet needed to stop a car that is traveling at 50 miles per hour?

A．55．

B．73．

C．128．

D．183．小题2:What is the braking distance for a car that is travelling at 60 miles per hour?

A．66 feet．

B．119 feet．

C．185 feet．

D．251 feet．小题3:Which of the following statements about braking and speed is true?

A．The braking distance is what it takes for the driver to react to a danger that he sees．

B．The speed of a car has a direct effect on the distance needed to stop the car．

C．The braking distance increases only when a driver drives faster than 50 miles per hour.

D．Driving slowly can help a person to avoid all accidents

通信协议中规定了对等实体之间信息传输的基本单位，它是由（3）所组成的，在协议中，关于"数据的组织方式"是属于（4）要素。

空白处（3）应选择（）

A.控制信息和用户数据

B.协议数据和用户数据

C.协议数据和控制信息

D.用户数据和校验数据