问题
选择题
某交流电电源电压的瞬时值表达式为u=6 sinl00πt（V），则下列说法中正确的是（ ）A．用交流电压表测该电源电压时，示数是6V B．用交流电压表测该电源电压时，示数是6 C．用此电源给电磁打点计时器供电时，打点的时间间隔为0.01s D．把标有“6V 3W”的小灯泡接在该电源上时，小灯泡将被烧毁 |
V
答案
答案：A
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| 某交流电电源电压的瞬时值表达式为u=6sinl00πt（V），则下列说法中正确的是（ ） A．用交流电压表测该电源电压时，示数是6V B．用交流电压表测该电源电压时，示数是6 C．用此电源给电磁打点计时器供电时，打点的时间间隔为0.01s D．把标有“6V 3W”的小灯泡接在该电源上时，小灯泡将被烧毁 |
答案：A
| 阅读理解。 | ||||||||||
| Here is a page from a magazine called Future. Read the following information about things that may happen in twenty years. Cars will run on solar power (太阳能) and will be much cleaner and safer. For example, if you are too close to another car or if you are driving dangerously, your car will slow down or stop by itself. New cities will have to be built in the sea. Some cities on water will have two levels (层). People will live on the upper level, the lower level will be used for traffic, shops and factories. Biotechnology (生物技术) will make food better and healthier. Plants without insects or illnesses (病虫害) will be developed. The taste of fruit and vegetables will be better and food will be kept longer. Many new ways to cure (治愈) illnesses will be found. People will use products of genetic engineering (基因产品) to cure more illnesses. However, some new illnesses will appear. | ||||||||||
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