题目

尼龙是世界上最早的人工合成纤维，它是从（ ）中提炼出来的。 A . 石油 B . 天然气 C . 煤炭 D . 岩石 答案：A25、 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 following chart shows the distance that it takes to stop a car at a given speed．The distance is measured in feet．The shaded area 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 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． 2．What is the braking distance for a car that is traveling at 60 miles per hour? A．66 feet．      B．119 feet．     C．185 feet．         D．251 feet． 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