阅读下面短文，从A、B、C、D四个选项中选出最佳选项。

Where does the wind come from? What makes the wind move(移动) all the time? Scientists tell us that it is the sun. That makes air move, and makes it blow(吹). When the sun shines on the earth, it makes the earth hot. Then the earth makes the air hot. When the air becomes hotter, it also becomes lighter(更轻). The light air goes up. Cool air comes into take the place of（代替） the hot air. The hot light air goes up higher and higher until it becomes cool. Then it comes down again, and then the earth makes it hot again, and it has to go up. When the air move, it has wind.

弥勒市白昼时间最长的一天是（    ）

-- It's snowing. I really want to run outside and make a snowman.

--           Why not have a snow ball fight instead? It's more exciting.

化简与求值：

（1）化简：$\frac{1+\tan 15°}{1-\tan 15°}$；

（2）已知α，β都是锐角，cosα=$\frac{1}{7}$，cos（α+β）=﹣$\frac{11}{14}$，求cosβ的值．

依照下面的例句，运用相同的修辞手法，写出你对书的认识
         书是益友——臧克家说：“读过一本好书就象是交了一个益友。”
         书是钥匙——托尔斯泰说：“理想的书籍是撕开智慧之门的钥匙。”
         书是   ——我说：“                                              ”