第4部分：阅读理解（第31~45题，每题3分，共45分）
下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。
　 
             第一篇  Heat and Health
　
　  Extremely hot weather is common in many parts of the world.Although hot weather just makes most people hot,it can cause medical problems-and death.
Health experts say that since the year 1900,extremely hot weather has killed more people in the United States than  any other natural event.One year-the unusually hot summer of 1980-heat caused about 1,700 deaths in the United States.In 1995,more than 600 people died in a similar heat wave in one city-Chicago.
To measure extreme heat,govemment weather experts have developed the  Mean Heat Index.It measures the average of how hot it is felt all day on an extremely hot day.Experts say it is the total heat of a hot day or several hot days that can affect health.Several hot days are considered a heat wave.Experts say heat waves often become deadly when the nighttime temperature does not drop much from the highest daytime temperature.
The most common medical problem caused by hot weather is heat stress.Usually,it also is the least severe.For most peoople,the only result of heat stress is muscle pain.The pain is a warning that the body is becoming too hot.Doctors say drinking water will help the pain disappear after the body again has the right amounts of water and salt.For some people,however,the result is much more serious.
For example,doctors say some people face a greatly increased danger from heat stress.These people have a weak or damaged heart,high blood pressure,or other problems of the blood system.Severe heat can help cause a heart attack or stroke.Health experts say this is the most common cause of death linked to hot weather.
　
31.How many people died from heat in Chicago in 1995?
A.About 1700.
B.Nearly 1900.
C.Around 1100.
D.Over 600.
　
32.What can people learn from the Mean Heat Index?
A.The average temperature of an extremely hot day.
B.The highest temperature of an extremely hot day.
C.The lowest temperature of an extremely hot day.
D.The nighttime temperature of an extremely hot day.
　
33.A heat wave is a period of time during which
A.the weather is much better than usual.
B.the nights are much longer than usual.
C.the weather is much hotter than usual.
D.the days are much longer than usual.
　
34.Muscle pain in hot weather means that your body needs
A.more exercise.
B.more water.
C.less oxygen.
D.less sugar.
　
35.For people who are in extremely poor health,heat can be
A.deadly.
B.painful.
C.helpful.
D.stressful.