一辆汽车以25m/s的速度在平直路面上匀速行驶时，汽车发动机产生的牵引力为1000N，效率为30％，一次行程为250km，汽油的热值为4．6×10⁷ J／kg。求：
（1）在这次行程中汽车发动机所做的功是多少J？
（2）汽车至少要加多少kg汽油？

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   These years, with the development of society(社会), more and more teenagers have suffered from stress. Some of the problems can make them feel very w ____  and unhappy all day. Who can help them? A teacher from a college tried his best to help them. He thought of a lot of w____  to help them. On Monday and Thursday, you can c____  his hotline. Here are some ideas how to keep the young men healthier in every way.
   F____ , it is very important to keep healthy. To get e ____  sleep every day is also necessary. Try to have a healthy d____ every day. Secondly, maybe you are not the top student. It doesn’t m ____ . The most important thing is to work hard. If you try your best, your teachers and parents will understand you. If you have some problems, you should be a____   to talk with your teachers and parents. They can help you. Remember to s____  your happiness and s____   with your good friends. Sometimes you can go out for a walk.
In a word, you can try to make you happy by yourselves. I’m sure you can be happy every day.

明朝中期的中国，是一个综合实力走在世界前列的强国，但中国人没有恃强凌弱，郑和下西洋是世界上公认的和平之旅，28年间，郑和船队始终奉行“共享太平之福”的对外政策，发展与各国的友好关系，在中国与亚非国家之间架起了友谊的桥梁，进一步树立了中国的和平友好形象。