“谁言寸草心，报得三春晖。”这句话主要强调的是（　　）

自然界中的云、雨、雪、雾、露、霜等现象都是水的物态发生变化形成的．如图中对水的物态变化描述正确的是（　　）

根据短文内容，选择正确的选项。
    Early to bed and early to rise makes a man healthy, wealthy and wise.
    This is an old English saying. It means that we should go to bed early at night and get up early in the morning. If we do, we shall be healthy. We shall also be rich and clever.
    Is this true? Perhaps it is. The body must have enough sleep. Children of your age need ten hours' sleep every night. If you do not go to bed early, you can not have enough sleep. Then you can not think properly and you can not do your work properly. You will not be wise and you may not become wealthy!
    Some people go to bed late at night and get up late in the morning. This is not good for them. We should sleep at night when it is dark. The dark helps us to sleep well. When the daylight comes, we should get up. This is the time for exercise. If the body is not used, it will become weak. Exercise keeps it strong.
    Exercise helps the blood to move around inside the body. This is very important. Blood takes nutrition (营养) to all parts of our bodies. The brains in our heads also need blood. We think with our brains. If we keep our bodies healthy, and take exercise, we can think better!
Our bodies also need air to breathe. Without air we will die. Get up early in the morning and we can have plenty of clean, fresh air. That will keep us healthy and happy.