问题 单项选择题

与十进制数26.34375等值的二进制数是 (5) ,八进制数是 (6)

A.11010.1101

B.11010.01011

C.1011.1101

D.1011.01011

答案

参考答案:B

解析:

[分析]: 十进制数转换二进制数,整数部分用除2取余法,即不断用2去除,逐次得到的余数就是二进制整数部分由低到高的逐项的系数。小数部分用乘2取整法,即不断用2去乘,每次得到的整数就是二进制整数部分由高位到低位的二进制系数。所以 (26.34375)10(11010.01011)2,答案B。
由于八进制实际上是3位二进制的缩写表示方法,即将二进制数从小数点开始,整数部分向左,小数部分向右,3位(八进制)一组,不足部分添0。分组后,即可将各组的二进制转换成八进制数。所以(11010.01011)12=(32.64)8,答案C。

单项选择题
阅读理解

A device that stops drivers form falling asleep at the wheel is about to undergo testing at Department of Transport laboratories and could go on sale within 12 months.

The system, called Driver Alert, aims to reduce deadly road accidents by 20% - 40% that are caused by tiredness. Airline pilots can also use it to reduce the 30% of all pilot-error accidents that are related to fatigue.

Driver Alert is based on a computerized wristband. The device, worn by drivers or pilots, gives out a sound about every four minutes during a car journey. After each sound the driver must respond by squeezing the steering wheel (方向盘). A sensor in the wristband detects this pressing action and measures the time between the sound the driver’s response.

Tiredness is directly related to a driver’s response time. Usually, a watchful driver would take about 400 milliseconds to respond, but once that falls to more than 500 milliseconds, it suggests that the driver is getting sleepy.

In such cases the device gives out more regular and louder sounds, showing that the driver should open a window or stop for a rest. If the driver’s response continues to slow down, the sounds become more frequent until a nonstop alarm warns that the driver must stop as soon as possible.

The device has been delivered to the department’s laboratories for testing. If these tests, scheduled for six months’ time, are successful, the makers will bring the product to market within about a year.

小题1:According to the text, Driver Alert ______.

A.aims to reduce tiredness-related accidents

B.has gone through testing at laboratories

C.aims to prevent drivers form sleeping

D.has been on sale for 12 months 小题2:How should a driver respond to the sounds from Driver Alert?

A.By sounding a warning.

B.By touching the wristband.

C.By checking the driving time.

D.By pressing the steering wheel.小题3:We can learn form the text that the driver needs to stop for a break when his response time is ______.

A.about 400 milliseconds

B.below 500 milliseconds

C.over 500 milliseconds

D.about 4 minutes小题4:     When the driver gets sleepy while driving, Driver Alert ______.

A.moves more regularly

B.stops working properly

C.opens the window for the driver

D.sounds more frequently and loudly