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阅读理解
We all know the sun is important. It provides life for plants, animals, and people here on Earth. But how does the sun do that? It's the sun's energy that makes life on our planet possible.
Energy from the sun is called solar (太阳 
) energy. It comes in the form of light or heat. Solar energy is what makes you feel hot when you sit in the sunlight. People have used solar energy for thousands of years. Houses are built with windows so that sunlight can get inside and provide heat. The sun's energy can also be used to heat water and even food. If you own a magnifying glass (放大镜), your parents have probably warned you about leaving it in the sun. Solar energy can actually make the magnifying glass burn things under it, causing a fire. This type of energy from the sun in the form of heat is called solar thermal (热的) energy.
We can also turn the sun's light into electricity (电能). This is done with solar panels. Using this technology, we can run a calculator and even power cars. But what happens when groups of clouds block the solar panels? Does this mean that solar energy can only be used on bright sunny days? Solar panels can have batteries (电池) with them to store (储存) electricity for a rainy day. When the sun is shining, the electricity flows from the solar panel into the batteries. This stored electricity can be used at night or on cloudy days.
Do you know that solar energy is not as expensive as it used to be? In fact, in the last few years, solar panels have become much more affordable for people to use. Since the sun gives off more energy in one second than people have used since the beginning of tie, imagine what we could do if we used the sun's energy to power our earth.
