题干

小黄用右图装置测定铜锌合金中锌的质量分数和锌的相对原子质量。主要实验步骤如下(必要的固定装置已略去):

①连接装置并检查装置气密性;②加入药品和水;③如图所示,记录C中液面刻度(C为量气管,带有刻度的玻璃管,D为水准管); ④由A向B中滴加试剂至过量;⑤待B中不再有气体产生并恢复至室温后,记录C中液面刻度,计算得到气体的体积为V mL(经查,该气体密度为ρg/L);⑥将B中剩余固体过滤、洗涤、干燥并称重,称得剩余固体质量为W g。请根据上述实验步骤,回答下列问题:

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 We all know that exercise is good for your health. But some kinds of exercise may be better than others. Running, for example, may help to protect against heart disease and other health problems. Running may also help you live longer.

 Recently, researchers studied more than 55,000 adults. About a quarter of the adults have a good habit of running. The study found these runners were much healthier than non-runners. In fact, the runners lived, on average(平均), three years longer than the non-runners.

 Running may be good exercise, but it can be difficult on the body. Here are commonly shared ideas among fitness experts(健身专家) to lower the risk of injury(受伤) for people who are new to running.

⊙Take it easy.

 Do not run too much, too soon or too fast. Most people get running injuries when they push themselves too hard. The body needs time to get used to increases in distance(里程) or speed.

⊙ Get good running shoes.

 There is no single best shoe for every runner. You should find the shoe that offers the best fit and support for your feet. More importantly, you should have a new pair of shoes every 500 to 800 kilometers.

⊙Take good notes.

 Take time after each run to write down notes about what you did and how you felt. Look for things that happen again and again. For example, you may find that your knees hurt when you run sometimes. But perhaps you feel great when you have a rest between running days. These notes will help you make the best plan for running.