A young father was visiting an old neighbor. They were standing in the old man’s garden, and talking about children. The young man said,“How strict should parents be with their children?”
　  The old man pointed to（指着）a string (细绳) between a big strong tree and a thin young one.
　 “Please untie (解开) that string.” said the old man. “But first pull the string tight so that（以便于）the young tree is straight again.” The young man did so. He untied the string and only found that the young tree bent（弯）over to one side.
　 Then the old man said,“There, it is the same with children. You must be strict with them. But sometimes you must untie the string to see how they are getting on. If they are not yet able to stand alone，you must tie the string tight again. But when you find that they are ready to stand alone，you can take the string away.”

设a，b，l均为不同直线，α，β均为不同平面，给出下列3个命题：

①若α⊥β，a⊂β，则a⊥α；

②若α∥β，a⊂α，b⊂β，则a⊥b可能成立；

③若a⊥l，b⊥l，则a⊥b不可能成立．

其中，正确的个数为（　　）

阅读下面材料，根据要求作文。

    两马各拉一货车。一马走得快，一马慢吞吞。于是主人把后面的货全搬到前面。后面的马笑了：“越努力越遭折磨！”谁知主人后来想：既然一匹马就能拉车，干嘛养两匹?最后懒马被宰掉吃了。这就是经济学中的“懒马效应”。

    请根据阅读后的感悟和联想，写一篇不少于800字的文章。

要求：①自定立意；②自拟标题；③除诗歌外，文体不限；④不要套作，不得抄袭

这腰鼓，使____的空气变得____了，使____的阳光立即变得____了，使____的世界立即变得____了。

A．冰冷        B．恬静        C．燥热

D．亢奋        E．困倦        F．飞溅