It's a wonderful, warm summer day without a coud in the sky. You're outside, and you can feel the sun's heat on your skin. Do you know what else you are feeling? You're feeling the sun's energy! Without it, the earth would be a cold, dark, lifeless place The sun's radiation(辐射) gives us light and heat energy.

 The Sun's radiation can be harmful to us as well. We can't see it, but ultraviolet(紫外线) radiation comes from the sun along with heat and light. You can not see ultraviolet radiation, but it influences our health. Ultraviolet radiation is what burns our skin.

 Ultraviolet radiation has three parts: ultraviolet radiation A, ultraviolet radialion B, and ultraviolet radialion C. Waves of ultraviolet radiation  A and B may cause harm to our body when we get sunburned. The harm to our body can give us skin cancer(皮肤癌) and cause other health problems.

 You can help to protect yourself from ultraviolet radiation by wearing sunscreen(防晒霜), sunglasses and hats.

 Try to stay out of the sun when it is especially strong .You can find out ultraviolet radiation levels by watching the weather report on television.