Why the Earth Is Round？

Our never-thought to ask question for today is： Why is the earth round？ Why not a cube？ A cube？ No， thats silly. Is it？ Why？ Because…， because really big things like to be round for some reason. Exactly right. And that reason is gravity.

Think of it this way. Suppose the earth were a cube. Then some points on its surface would be farther away from the center than others. The corners， for example， would be much farther out than the rest.

Since gravity works equally on everything， there would be a tendency to pull those uneven places down. The surface would even itself out. The only geometrical object in which every point on the surface is the same distance from the center is a sphere. But wait a minute， Ive seen pictures of asteroids that have all sorts of crazy shapes. Why arent they round？ Only because they arent big enough for gravity to be a determining factor. If an asteroid were to suddenly become as big as a moon， it would indeed rearrange itself gradually into a sphere.

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废寝忘食并不能有效提高成绩！

哈佛大学一项关于“决心”的研究表明，“废寝忘食”学习并不能学好。

人们认为，争取优秀的孩子为了追求高分，一般都要做出额外牺牲，比如睡得少，或者饮食不规律。

但是一项针对4 000名英国青少年的新研究表明，那些展现出决心、勇气和坚持的学生一般会有更健康的生活方式。

哈佛大学教育研究生院的研究结果表明，“那些有决心的孩子更可能照顾好自己，培养健康的情感管理技能，而不是养成不利于健康的行为方式。”

之前已有研究表明，考试压力过大对儿童的健康不利。凯洛格上个月发表的一项调查发现，年仅10岁的孩子就通过吸烟、吃糖果、喝能量饮料来备考。

哈佛大学教育研究生院的教员克里斯提娜·辛顿说：“研究结果表明，追求好成绩的决心并不需要不惜一切代价来逼自己，而是要培养健康的情感管理技能，学会高效的学习方法。”