阅读下列句子，根据所给开首字母，写出符合句子意思的本学期所学单词，注意必要的形式变化。

小题1:There are two hundred boys r_______ from seven to fourteen in age.

小题2:Dr. Yuan Longping searched for a way to increase a rich h_______ without increasing the area of fields.

小题3:When Liu Xiang won the 110-metre hurdle race, he was s________ by the clicking cameras of the media.

小题4:You’d better b________ yourself or else you’ll be in deep trouble when Mr. Wang comes in.

小题5:The Spring Festival Gala has developed into an occasion that most Chinese find it hard to ignore, and millions of v________ are watching the performance being broadcast live.

若圆柱的底面半径为5cm，高为4cm，则圆柱的侧面积为（）平方厘米。