先通读下面的短文，然后根据短文内容，在空格内填入一个最适当的词，所填单词必须在答卷标有题号的横线。每空只能填一字

What is a hurricane?(飓风)

    You may already know that hurricanes are storms that can cause devastating(毁灭性的) waves, wind, and rain. They happen during “Hurricane Season,'' from June 1st until November 30th in the Atlantic Ocean and from May 15th until November 30th in the Pacific Ocean.

Categories(类别)of Hurricanes

    There are five categories of hurricanes, which are based on wind speeds. The categories help people know how much damage(危害) a hurricane may cause because the greater the wind speed, the more dangerous the storm. For example, a Category 5 hurricane has winds over 155 miles per hour, which are strong enough to break the buildings along the seaside completely.

Hurricane Dangers

    When a hurricane happens together with heavy rainfall（降雨）, there can be a devastating flood. The centre of a hurricane is called the eye. While most of a hurricane has dangerously strong winds, the eye in fact is a calm area in the storm. When the eye of a hurricane passes over land, people might think that it's over, but before long the wind and rain increase(增长) again as the second part of the hurricane moves through.

Hurricane Safety Tips

    There is no way to stop a hurricane or make it change direction, so if you ever find yourself in the path of a hurricane, be sure to stay inside during the storm. You could be seriously injured(受伤) if you go outside.

    The purpose of keeping fit is to avoid illness ,resist the mental and physical fatigue（疲劳）that make us more likely to contract infections ,and above all to feel more pleasure in being alive. Research has shown the value of a balanced diet ,fresh air, sunshine ,enough rest and some forms of regular exercise for everyone .If everyone followed this plan ,the number of people visiting the doctor and going to hospital would be considerably reduced.

    Unfortunately, although most people acknowledge the importance of physical fitness, not enough of us put this into practice .We spend too much time watching others from the comfort of an armchair or a seat in the stand at a sports stadium.

    One reason why people who are physically fit to live longer is that they do not put the heart under excessive strain（过度劳累）and so they reduce the risk of heart and blood vessel（血管）diseases .They also avoid suffering the consequences of weakened muscles ,which are the cause of a great deal of back and abdominal（腹部的）trouble.

    About 640 muscles for about 45% of our body's weight, they must have the ability to store energy and be continually supplied with fuel by the blood .Sensible exercise, suited to each individual and preferably undertaken on the advice of a doctor, is the best insurance of meeting these requirements.

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