如图，∠AOB为直角，∠AOC为锐角，且OM平分∠BOC，ON平分∠AOC，求∠MON的度数．

 

小明学习“人口与人种”这一节后，对人口的增长、分布、人口问题、密度等方面作了如下归纳，其中错误的一项是（  ）

听短文，在短文中填写所缺单词
    Tom is a____boy. He is eleven years old. He's two years younger than his____, Jim. Tom is 150cm and Jim is 160cm. Jim is 50 kilos and Tom is 60 kilos. Tom wants to lose some weight, so he tries not to eat too much____. He also____more exercise than____.
    ____morning he gets up earlier than Jim and he goes____for____minutes. He usually does it after school. After dinner, Tom often goes for a ____, and Jim likes____at home. Now Tom is much____than Jim. Jim thinks he____more exercise now. He and Tom will do exercise tighter.

名著阅读，根据要求选择或作答。

下列图象中所发生的现象与电子的跃迁无关的是（　　）