问题
问答题
光线与镜面成60°角射在平面镜上，如图所示，试画出反射光线，并标出反射角的度数．
答案
首先做出法线，入射光线与镜面的夹角是60°，所以入射角为90°-60°=30°．根据反射角等于入射角做出反射光线．反射角也为30°．如图所示：
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光线与镜面成60°角射在平面镜上，如图所示，试画出反射光线，并标出反射角的度数．
首先做出法线，入射光线与镜面的夹角是60°，所以入射角为90°-60°=30°．根据反射角等于入射角做出反射光线．反射角也为30°．如图所示：
| 阅读理解。 | |||
| On March 11th, 2011, an earthquake (地震) happened in Japan. More and more people worried about the problem of radiation. But how can we protect (保护) ourselves from radiation? Here are some suggestions (建议) for you.
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| 任务一：根据短文内容，判断正（T）误（F）。 ( )1. Often open the windows and doors, so we can protect ourselves from radiation. ( )2. Often wash clothes with clean water, so we can protect ourselves from radiation. 任务二：根据短文内容，填上所缺的内容。 3. The underlined word "radiation" in Paragraph One means _____ in Chinese? 4. _____ can help us breathe (呼吸) better air. 任务三：根据短文内容，选择正确答案。 5. Which fruit can help us protect ourselves from radiation? A. Tomatoes. B. Cabbages. C. Oranges. D. Turnips. |