从温度表的读数来看发动机水温已上升到沸点，但水箱口还未喷水，为什么一旦熄火后水蒸气立刻大量喷出？
参考答案：
发动机温度上升到沸点时，发动机的出水温度已达到沸点，但进水温度还未达到沸点。即使循环水水温全部达到沸点，由于水泵在工作，水流不断循环，进水口有吸引力，出水口有压力，它没有条件蒸发喷出。发动机熄火后水泵停止工作，散热水也停止循环，由于水流的惯性和水蒸气上升的趋势，大量的水蒸气从加水口喷出，而且带有一定压力，这个压力片刻后会逐渐减弱、消失。遇见此情况，不能急于打开水箱盖，否则蒸汽喷出会烫伤人。
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| In the United States, friends can be close, constant, intense, generous, and real, yet fade away in a shorttime if circumstances change. Neither side feels hurt by this. Both may exchange Christ- mas greetings for a year or two, perhaps a few letters for a while then no more. If the same two people meet again by chance, even years later, they pick up the friendship where it left out and are de- lighted. In the United States, you can feel free to visit people's homes, share their holidays, enjoy their lives without fear that you are tak ing on a lastinS obligation (负担). Do not hesitate to accept hospi tality (热情款待) because you can't give it in return. No one will expect you to do so for they know you are far from home. Americans will enjoy welcoming you and be pleased if you accept their hospi tality easily. Once you arrive there, the welcome will be full, warm and re al. Most visitors find themselves readily invited into many homes there. In some countries it is considered inhospitable to entertain (招待) at home, offering what is felt as only home-cooked food, not " doing something for your guest". It is felt that restaurant entertaining shows more respect and welcome. Or for other different reasons, such as crowded space, language difficulties, or family custom, out- siders are not invited into homes. In the United States, both methods are used, but it is often considered more friendly to invite a person to one's home than to go to a public place, except in purely business relationships. So, if your host or hostess___, do not feel that you are being shown inferior (差的,低级的 ) treatment. Don't feel neglected (被轻视的) if you do not find flowers a- waiting you in your hotel room, either. Flowers are very expensive there, hotel delivery is uncertain, arrival times are delayed, changed, or canceled (取消)-so flowers are not customarily sent as a welcoming touch. Please do not feel unwanted! Outward signsvary in different lands, the inward welcome is what matters, and this will be real. |
| 1. What's the best title of the text? ( Please answer within 5 words. ) ________________________________________________________________________________________ 2. Which sentence in the text is similar in meaning to the following one? Americans gladly continue their friendships after a chance encounter even if several years have passed. _________________________________________________________________________________________ 3. Fill in the blank in the fourth paragraph with proper words. ( Please answer within 6 words. ) __________________________________________________________________________________________ 4. For what purpose does the writer mention flowers in the last par agraph? ( Please answer within 15 words. ) _________________________________________________________________________________________ 5. Translate the underlined part in the second paragraph into Chi nese. _________________________________________________________________________________________ |