Each summer，you hear news that some sports players are sent to hospitals because it is too hot. Our bodies can't be outside in the sun for a long time. So in hot summers，be careful about playing sports outside.

    Firstly，to play sports safely in hot weather，you must drink water. Sports drinks are great for athletes，but they have so much sugar that they'll dehydrate（使脱水）you more. However，drinking a few bottles of sports drinks will be good for you.

    Secondly，be sure to take enough breaks to let your body rest. If your coach doesn't let you take enough breaks in the heat，don't wait until you feel uncomfortable. Just be honest with your coach when you need breaks.

    Thirdly，when you have a break，don't sit in the sun. With the sun beating down on you，you'll only heat up and sweat（冒汗）more. Take a seat under a tree，or even better，go indoors for a little while. Cooling yourself down can help you stay active longer.

    Fourthly，remember that the earlier in the day you start your exercise，the cooler it will be. If you can start practice before the sun comes up，you have a few good hours to practise in the cool hours of the morning. Also，the earlier you practise，the earlier you can finish the exercise. If you need more practice time，come back to the field later in the evening，when the sun is setting.

    Last but not least，you should watch what you eat. Eat food which is high in water，starch（淀粉）and carbonhydrate（糖类），but be sure to get a good balance in your diet.

    As long as you pay attention to the above，playing sports safely in the heat isn't a difficult thing.

为探究“温度对唾液淀粉酶催化作用的影响”，小丽同学设计了如下实验：

步骤一：收集唾液并与蒸馏水按1∶1的体积比制成唾液稀释液；

步骤二：取可溶性淀粉1克，放入烧杯中，加入99毫升，搅拌，缓慢加热，溶解，制成1%的淀粉溶液并冷却至室温;

步骤三：取4支洁净的试管编上号，按表中物质的量依次加入各试管并振荡，放置在一定温度下的水浴中保存10分钟；

步骤四：取出试管，分别滴加1滴体积分数为0.4%的碘酒溶液，然后摇匀。观察并记录各试管中溶液的变化情况如表。

（1）设置A组实验的目的是               ；

（2）收集唾液的方法是                     ；

（3）根据实验记录分析，实验结果所支持的实验假设是                     。

孟德尔遗传基本规律的精髓：生物体遗传的不是性状，而是____ ．