地球成为太阳系中唯一有生命的特殊行星，原因叙述正确的是（） A.地球所处的光照条件不

影响心排血量的因素有（）

A.前负荷

B.后负荷

C.周围组织需氧量

D.心室收缩的同步性

E.心率

附子的来源为

A．北乌头的主根

B．乌头的主根

C．草乌的块根

D．乌头侧根的加工品

E．草乌侧根的加工品

.

A device that stops drivers from falling asleep at the wheel is about to undergo(接受) 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 tiredness.

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 pressing the steering wheel. A sensor in the wristband detects this pressing action and measures the time between the sound and 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.

68. 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.

69. We can learn from 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

70. 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

71. 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 from sleeping

D. has been on sale for 12 months

国境口岸的卫生要求控制啮齿动物、病媒昆虫的数量降低到不足为害程度。( )

肺脓肿空洞的典型X线表现是（）

A.薄壁空洞

B.厚壁空洞

C.薄壁空腔

D.不规则偏心空洞

E.空洞壁厚伴有液平