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.

已知${\int }_0^2$（3x²+k）dx=16，则k=____ 

X、Y、Z是3种短周期元素，其中X、Y位于同一主族，Y、Z处于同一周期．X原子的最外层电子数是其电子层数的3倍．Z原子的核外电子数比Y原子少1．下列说法正确的是（　　）

如图所示，体积相同的甲、乙、丙三个物体浸没在水中的浮沉情况，此时甲、乙、丙三个物体所受的浮力分别为 、 、 ，则下面关系正确的是（   ）