All of us know that breakfast is very ____ 'nesəsərɪ to us. It is____of the most important meals of the day. To keep ____ (health), everyone should have a good breakfast.____ (eat)the right food is good for our health. We can have eggs, bread, milk and other food ____ breakfast.

    Many students go to school without breakfast.____  bɪ'kɒz they get up late or their parents don't cook for them. It's ____ for their health.

    Without breakfast children may not____grəʊfast and may not study and play very well at school. They may be easier to get____(ill). And when they're ill, it will____(take) them a long time to recover（恢复）. I think everyone should have some good eating habits.

某同学从定量角度研究双氧水制取氧气的过程，对原实验进行部分改进，增加了称量操作．具体做法是：取10%的双氧水和少量的二氧化锰放入气体发生装置，并对反应前后混合物的质量进行称量，记录如下：

若反应后，双氧水分解完全且氧气全部逸出，该同学得出的结论中，不合理的是（）

明朝的北京城是典型的大一统王朝的都城，它有三重，请问皇帝住在里面的哪一重（    ）