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    Everyone knows that exercise is important. We all need to exercise. Doctors say it's good for us. It keeps body strong.

    When the daytime comes, we must get up. This is the time for exercise. Exercise means doing things with the body. There're many ways to exercise. You can walk, run, swim, skate, or play ball games. Make sure you exercise in the following(下面的)ways: You have to like what you're doing. Exercise enough—but not too much. It's good to exercise twice each week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or three sports that feel right for you.

    Exercising can be fun. Friends can exercise together at a fitness center, or they can play sports together. How do you exercise?

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一只小灯泡标有“8V，4W”字样，若接在4V的电源两端，则其实际功率为____ W．工作5min产生热量____ J；现将该灯泡接在12V的电源上，为使其正常发光，应____联一个____Ω的电阻（假定灯丝电阻不变）．

18世纪的英国曼切斯特地区山清水秀，这里的桦尺蛾大多是浅色的，少数是深色的．100年以后，工业污染把树皮熏成了黑褐色，深色的桦尺蛾成了常见类型，浅色的却成了少数．造成这种变化的原因是（　　）

在探究“水温的变化对金鱼呼吸的影响”时，要研究的变量是（   ）

为下面这则消息拟写的标题最恰当的一项是（　　　）。（2分）
本报讯　8月13日晚，江西省展演中心座无虚席，来自南昌市各条战线的劳模英模代表，兴致勃勃地观看了由省委宣传部策划、创编的大型历史风情魔幻歌舞《神奇赣鄱》，度过了一个令人难忘的夜晚。
变幻莫测的灯光、神秘的时光隧道、优美的歌舞、540度全景多媒体；一会仿佛在水底，一会仿佛在神话世界，一会又到了魔幻世界……观众眼睛应接不暇。
看完《神奇赣鄱》，劳模英模代表们久久不愿离去。多次见义勇为、入选“中国好人榜”的范圣高看完演出后，兴奋地告诉记者：“在我们物质生活得到了大幅提高的同时，《神奇赣鄱》又给我们端上了一道精神文化‘大餐’。”