用测电笔可辨别火线和零线，如果氖管发光，表明接触的是____ ．小明同学在闭合开关后，发现电灯不亮，他用测电笔测试图中的a、b、c、d四点，只有a点不发光，那么可能发生的故障是____ ．

D

    It happens every night—bedtime. But what if you're not sleepy? Should you still go to bed if you are just going to lie there with your eyes wide open? It's a problem that has been around as long as there are people trying to sleep.

    You might be excited by something you did in the day. You might be nervous about what you're going to do the next day. Maybe you don't like sleeping alone in your room. Maybe you have frightening dreams. All of these are possible reasons for your sleeping problem. However, there are some steps you can take to help you solve it.

    One thing that can help is talking to a parent or another trusted adult about what you're worrying about at bedtime. For example, if you're nervous about taking a test, or upset about being teased (被嘲弄) at school, it can really help to tell somebody. Knowing that somebody has heard you can help ease your mind so that you can have a good rest.

    Sleeping in a comfortable bed in a quiet and cool room is a good choice. If there's anything in your room that makes you feel uneasy or anxious at night, like a picture that looks strange in the dark, or a noisy faucet (水龙头) in the bathroom, be sure to ask your parents to move or fix it. Make sure electronics, such as mobile phones or iPads, are kept away from your bed. They can keep you excited, making it harder for you to fall asleep.

    If you are usually restless around bedtime, doing certain things to relax beforehand may help you fall asleep. Try to take more time to wind down by taking a warm bath, or listening to a bedtime story at least 30 minutes before you go to sleep. It also helps to follow a bedtime routine and go to sleep at the same time every night. As a result, your body will get the message that it's almost time to sleep. Your body will know to start feeling tired.

    In order to find the right solution for you, it's possible that you understand what exactly is keeping you up at night. Getting a good night's sleep is worth the time and effort of finding the right solution to your sleeping problem.

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                                                                                爱与孤独
      ①爱和孤独是人生最美丽的两支曲子，两者缺一不可。没有爱的心灵会孤独，未曾体味过孤独的人也不可能懂得爱。由于怀着爱的希望，孤独才是可以忍受的，甚至是甜蜜的。
      ②不止—位先贤指出，—个人无论看到怎样的美景奇观，如果他没有机会向人讲述，他就决不会感到快乐。人终究是离不开同类的。一个无人分享的快乐绝非真正的快乐，而一个无人分担的痛苦则是最可怕的痛苦。所谓分享和分担，未必要有人在场。但至少要有人知道。永远没有人知道，绝对的孤独，痛苦便会成为绝望，而快乐——同样也会变成绝望！
      ③交往为人性所必需，人生之常态，而它的分寸却不好掌握。帕斯卡尔说：“我们由于交往而形成了精神和感情，但我们也由于交往而败坏着精神和感情。”我相信，前—种交往是两个人之间的心灵沟通，它是马丁•布伯所说的那种“我与你”的相遇，既充满爱，又尊重孤独；相反，后一种交往则是熙熙攘攘的利害交易，它如同尼采所形容的“市场”，既亵渎了爱，又羞辱了孤独。相遇是人生莫大的幸运，在此时刻。两颗灵魂仿佛同时认出了对方，惊喜地喊出：“是你！”人一生中只要有过这个时刻，爱和孤独便都有了着落。