T14次列车从上海始发，途经蚌埠、济南等城市，最后到达北京．T14次列车时刻表如下，由时刻表可知，列车在蚌埠至济南区间段运行过程中的平均速率约为（ ）
T14次列车时刻表
| 停靠站 | 到达时刻 | 开车时刻[ | 里程（km） |
| 上海 | ┅┅ | 18：00 | 0 |
| 蚌埠 | 22：26 | 22：44 | 484 |
| 济南 | 03：13 | 03：21 | 936 |
| 北京 | 08：00 | ┅┅ | 1463 |
A．100km/h
B．150km/h
C．200km/h
D．180km/h
列车22：44时刻从蚌埠开出，03：13到达济南，经历时间为t=4.47h
通过的里程是S=936km-484km=452km
则平均速率为
=. v
=101km/hS t
故选A
Each summer, you hear news about a sports player being rushed to the hospital or passing out because the heat was just too much. If you follow some basic safety tips, you’ll be safe and happy playing outside for years to come. Drinking water is crucial to your health in the heat. This is the first thing that everyone says when it is hot outside. You should not drink soda, coffee, or iced tea when you’re playing outside, and for a few hours after you get inside too. Be sure to take enough breaks to let your body rest. If you feel that your coach don’t let you take enough breaks in the heat, don’t wait until you feel awful to march to the sidelines. Once you feel bad, it’s usually too late. Just be honest with your coach when you need breaks. He’ll understand. When you do have a break, don’t sit in the sun. With the sun beating down on you, you’ll only heat up and sweat more. Try to grab a seat in the shade under a tree, or even better, go indoors for a little while. Cooling yourself down can help you stay active longer. The signs of dehydration（脱水）can be tough to recognize. They include a dry or sticky mouth, dry skin, a headache, and dizziness（头晕）. You might not always feel thirsty, so watch out for the signs of dehydration, and get yourself into the shade and get some water before it gets worse. The earlier in the day you start your workout or practice, the cooler it will be. If you can start practice before the sun comes up, you have a few good hours to practice in the cool hours of the morning. Also, the earlier you practice, the earlier you can be done, which gives you some good recovery time when the heat gets bad in the afternoon. If you need more practice time, a good idea is to take a break when the heat is bad and come back to the field later in the evening, when the sun is setting. As long as you pay attention to the above, playing sports safely in the heat isn’t a difficult thing. Title: Some safety tips while playing sports in the heat
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