两盏灯L1和L2，分别标有“220V25W”和“220V100W”字样，则两灯的_爱下问搜题

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问题填空题

两盏灯L₁和L₂，分别标有“220V 25W”和“220V 100W”字样，则两灯的电阻之比R₁：R₂=______，若将它们串联接入照明电路中，L₁和L₂的实际功率之比P₁：P₂=______，灯______较亮一些．

答案

（1）∵由R=

U

2额

P额

得：R1=

(220V)2

25W

，R2=

(220V)2

100W

∴R₁：R₂=4：1

（2）当两灯串联时，由P=I²R得：

P₁：P₂=R₁：R₂=4：1

L₁的实际功率大，所以L₁亮

故答案为：4：1，4：1，L₁．

完形填空

Mrs. Ball had a son. His name was Mick. She 　26　him very much and as（因为）he was not a 　27　child, she was always afraid that he might 　28　ill. 　29　she usually took him to see the best 　30　 in the town four times a year and asked the doctor to look 　31　the son.
　 During one of these 　32　, the doctor gave Mick all kinds of tests(检查) and then said to him, “Do you have any trouble with your nose or ears ?” Mick 　33　for a second and then answered, “Yes, I 　34 _.”
　 Mrs. Ball was very 　35　. “But I’m sure you have 　36　told me that, Mick!” she said worriedly. “Oh, really?” said the doctor 　37　. “And what trouble do you have 　38　your nose and ears, my boy?” “Well,” answered Mick. “I always have trouble with them when I’m 39　my sweater off, 　40　 the collar (领子) is very tight (紧的).”

A．after　　

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