如图所示的电路中，电源电压保持不变。闭合电键S后，电路正常工作。过了一会儿，两个电表中只有一个电表的示数变大。灯L和电阻R中的一个可能出现了故障。①若灯L发光，则故障是 ；②若灯L不发光，则故障是 。
电阻R短路 电阻R断路
题目分析：本题是灯与电阻的串联电路，电压表测电阻两端电压，电流表测的是串联电流。串联电路中电流只有一条路径，如果一个用电器断开，所有用电器都不能工作。若灯L发光，说明电路中有电流，灯泡正常，只有可能是电阻R短路，相当于导线，电阻为零，电阻两端电压为零。若灯L不发光，电路可能是断路，也可能是灯L短路，若灯L短路，则电流表和电压表示数都会变大，所以灯L不短路；若灯L断路，则电路中没有电流，电阻R两端也没有电压，不符合题意；若电阻R断路，电路中没有电流，电流表示数减小，但电压表正、负接线柱分别能与电源的正负极相连，所以电压表仍有示数，且等于电源电压，所以电压表示数增大，符合题意。
I had said goodbye to my husband, Joe, so often, but this time was . We now had our first child. After nights of talks, we made the difficult that Joe would go by himself to Alabama for the six-month training course, and I would stay behind with our new son. It was important that I my teaching position（职位）near our home at Fort Hood. Also we were part of a strong network of friends whom I could turn to for help. On Joe's evening at home, I bathed little Joey, got him into his sleeper and was heading to the bedroom when Joe gently touched on the shoulder. Lifting the baby from my arms, he said he wanted to put Joey to bed tonight. They headed down the hall, and I busied myself with meaningless tasks, Joe to appear from the bedroom within a few minutes. A half hour went by, and still he had not come back. Thinking he was having getting our son to fall asleep, I walked quietly to the baby's room and looked into the dimly-lit（灯光暗淡的）room. Sitting in the rocking chair, moving slowly back and forth, was my husband with tears（眼泪）in his eyes. He was holding our baby in his arms he had fallen asleep long before. When his pained eyes met mine, he said, "I just can't put him down." That night we stood over Joey's bed, holding each other and saying over and over that we would make it through this leaving and be again soon. Joey is six now, and he has a four-year-old brother named Jack. There have been many goodbyes since that night, yet my soldier still fights back tears when it's time to once again in service to his country and give his boys that last, long hug（拥抱）goodbye.
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