我国家庭电路的额定电压为 ______V；经验证明，只有不高于 ______V的电压才是安全的；为了防止家庭电路中电流突然增大造成的危害，电路中必须连入 ______；为防家用电器的金属外壳带电而造成触电事故，许多家用电器的电源插座是三孔的，这种三孔插座中有一根导线是与 ______相连的．
①我国家庭电路的额定电压为220V，经验证明只有不高于36V的电压才是安全的；
②电路中串联接入保险丝，保险丝当电路中电流增大时因发热熔断自动的切断电路，保护电路（用电器）；
③设置三孔插座，其中上面一个孔中的导线是与大地相连的，当家用电器的金属外壳带电时，漏电保护器能自动跳闸而切断电路，避免人触电．
故答案为：220，36，保险丝，大地．
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| In a small village, there lived a potter(陶工)who had a donkey(驴). Every day his donkey would carry soil from the 1 to his house. Since the field was quite 2 off, the potter would rest under a tree midway, 3 his donkey nearby. One day, the potter 4 to take the rope with which he tied the donkey every day. When he reached the 5 , he thought, "How do I tie this donkey today? He might 6 if I sleep." The potter decided to lie down holding the donkey's 7 while sleeping. But this way the donkey wasn't 8 nor was the potter able to take a good rest. A saint(圣人), who 9 to be passing by, saw the potter holding on to the donkey's ears. When the potter told the saint what the 10 was, he said, "Take the donkey to the place where you tie him every day. 11 to tie him using an imaginary rope. He won't run away." The potter did what the saint had said. He left the donkey and went to take a 12 . When he woke up, to his 13 and relief, he found the donkey standing in the 14 place. Soon the potter prepared to leave for home. 15 the donkey didn't move. "What's wrong with the donkey?!" 16 the potter in frustration(懊恼). 17 , the potter saw the wise saint again. He ran up to the saint and told him about the donkey's 18 behavior. The saint said, "You tied up the donkey, but did you untie him? Go and pretend(假装) to untie the rope." The potter 19 the saint's advice. Now the donkey was ready to leave for home. The potter understood that donkey was a 20 donkey. The potter thanked the wise saint and went home happily with his donkey. | ||||
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