洋葱鳞片叶内表皮细胞不含叶绿体．（判断对错）

目前绿色环保电冰箱采用了R600、R134a、环戊烷等制冷剂，作为氟利昂的替代品，充当热的“搬运工”，把冰箱里的“热”“搬运”到冰箱外面，因为它们可以像氟利一样即容易汽化也容易液化．有关这种电冰箱工作过程的下列说法，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.