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某变电所新装GGF-300型蓄电池共118个，验收时以30A的电流放电，测得电压为236V，停止放电后蓄电池组电压立即回升到253.7V，求蓄电池总内阻r和每个电池的内阻r′。

答案

参考答案：r==0.59（Ω）r′==0.005（Ω）

单项选择题

依据《中华人民共和国劳动法》规定，从事（）的劳动者必须经过专门培训并取得作业资格方可上岗作业。

A.特种作业

B.国外工作

C.危险工作

D.艰苦工作
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填空题

Are you looking after yourself


1. Running is an excellent exercise. Before you start running, you should warm up first, using slow movements that make all your muscles work. But be careful! If you stretch when your muscles are cold, you might do yourself an injury. Always wear comfortable clothing and make sure your trainers comfortable and in good shape. If you wear shoes that give good support to your whole feet, you will put less pressure on your knees. You should start exercising slowly, at a pace you can keep up for about 15-20 minutes. Try to exercise on soft ground as this will protect your knees and hips from too much stress.
2. It’s OK if you go to bed late occasionally but if you regularly cut down on your sleep, it will soon start to have a bad effect on your skin. If you get a good night’s rest, it will do your appearance the world of good. It is not called beauty sleep for nothing! Lack of sleep can cause acne or dry skin. Make sure you get a good night’s sleep by going to bed and getting up at regular times: don’t burn the candle at both ends. During the day, keep active: if you don’t get enough exercise during the day, you may end up sleepless all night.
3. Did you know that standing, sitting and walking badly can make you look heavier than you really are If we watched the way we sat and stood, it would improve our appearance a great deal. Stand in front of the mirror with your feet apart and your legs straight. Pull in your tummy, check that your ears, shoulders, hips, knees and ankles are in line with each other. You should be feeling and looking better already.
4. Most of us live in large polluted cities. If we got more fresh air, we would look healthier and more attractive. A brisk walk is one of the best things you can do for your circulation and appearance. Walking slowly is useful but a quick pace gets more oxygen into your lungs. So don’t just go for a pleasant stroll, try and find an area that doesn’t have much pollution, and get moving!
5. Many young people feel guilty about eating too much chocolate, and some even say they are addicted to it, though there is no evidence to support this. Chocolate does contain a lot of fat, and therefore any addicts out there would do better to eat less. However, if your diet is balanced, you needn’t feel guilty: eating chocolate in moderation is free — but don’t eat it instead of a proper meal!
A. A good night’s rest
B. More leisure time
C. Good posture
D. Drug addiction
E. More fresh air
F. Balanced diet
G. Tips for a run

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