根据下面短文内容，回答题。
Heat Is Killer
Extremely hot weather is common in many parts of the world. Although hot weather just makes most people feel hot, it can cause serious medical problems---even death. Floods, storms,volcano eruptions and other natural disasters kill thousands of people every year.__________(46)
Experts say heat may be nature&39;s deadliest killer. Recently, extreme heat was blamed for killing more than one hundred people in India. It is reported that the total heat of a hot day or several days can affect health.___________(47) Experts say heat waves often become dangerous when the nighttime temperature does not drop much from the highest daytime temperature. This causes great stress on the human body.
__________ (48) out of the sun, if possible. Drink lots of cool water. Wear light colored clothing made of natural materials; avoid wearing synthetic clothing. Make sure the clothing is loose, permitting freedom of movement. And learn the danger signs of the medical problems, such as headache and vomiting that are linked to heat.__________(49) The pain is a warning that the body is becoming too hot. Doctors say those suffering headache or muscle pain should stop all activity and rest in a cool place and drink cool liquids. Do not return to physical activity for a few hours because more serious conditions could develop.
Doctors say some people face an increased danger from heat stress. __________ (50) Hot weather also increases dangers for people who must take medicine for high blood pressure, poor blood flow, nervousness or depression.
第46题___________ 查看材料

A. Such persons have a weak or damaged heart， high blood pressure， or other problems of the blood system
B. Several of these conditions are present at the same time
C. Most people suffer only muscle pain as a result of heat stress
D. Several hot days are considered a heat wave
E. So does extreme heat
F. Doctors say people can do many things to protect themselves from the dangers of extreme heat