题干

图甲所示是定值电阻R0和灯泡L的U﹣I图象,现将定值电阻R0与灯泡L接入如图乙所示的电路中,电源电压不变,当S1、S2、S3闭合时,灯泡L恰好正常发光,此时R0消耗的电功率为3.6W;当S1闭合,S2、S3断开时,把滑动变阻器的滑片P移至中点,变阻器消耗的功率为P1;把滑片P移至b点,变阻器消耗的功率为P2,且P1:P2=9:8.下列说法不正确的是(   )

A:定值电阻R0的阻值为10Ω

B:灯泡L的额定功率为4.2W

C:滑动变阻器的最大电阻为15Ω

D:电源电压为6V

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C

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    When someone becomes an annoying presence for you, it means a disaster if you can't face it bravely and overcome it. I learned this 1 in the second year in high school. The shock this experience brought was so great that I felt my 2 was left on the side of the road for dead. That was all it took; one year and one person 3 everything.

    Her name is Jenny. She was the girl who 4 raised her hand and had useful comments about everything. When teachers needed challenging problems answered, they 5 her. And if students needed 6, they went looking for her. I didn't 7 her, but I admit her presence annoyed me. In the first year, as a model student, I was the person everyone 8 and all the teachers trusted. Then she came out of 9! We also had two classes 10. There I got to see what everybody thought of her. When an exam finished, it became a 11 that she got the top grade and it didn't 12 to my classmates whether I was right there, 13 I also got excellent grades. They would cross a desert and 14 her! I was left being denied my presence.15. I felt like not trying anymore.

    I stopped trying to put on a show because no one was 16 anymore. Later, I volunteered at the graduation ceremony. She was palled to make a(n) 17 and discussed their difficulties. I realized all her hard work got her there, not her desire to 18. It finally hit me that Jenny 19 the attention she got. She showed me how big the world is and how 20 a world I used to live in. I'll do my best because I know it will pay off.