题目

一段电阻线,当加10 V电压时,流过它的电流为0.2 A,其电阻为50Ω,将电压减小为5 V,则它的电阻为___Ω,当电压减小为零时,其电阻为______Ω,原因是_______________________________________________。 答案：【答案】5050电阻是导体本身的一种性质,与它两端的电压无关【解析】电阻是导体本身的一种性质，电阻的大小取决于材料、长度、横截面面积，与电阻两端电压无关；所以将电压减小为5V，则它的电阻仍为50Ω，当电压减小为零时，其电阻还是50Ω.动词运用(共10小题。计10分)用括号内所给动词的适当形式完成下面短文，必要时可加助动词。(请将各小题的答案写在短文后相应的横线上。)Mr and Mrs Smith were giving a dinner party with 20 visitors seated around a table. Their talk was about who 【小题1】      (have) more self-control(自我控制力 )，men or women. Suddenly they saw a strange expression ( 表情 ) 【小题2】      (come) across Mrs Smith's face. She said something to the servant(仆人) standing behind her without 【小题3】      (turn) around. The servant quickly put a glass of milk outside the open door. One of the men said,  "I want to know what self-control everyone 【小题4】     (have). While I 【小题5】      (count) from 1 to 300, none of you can move at all. If you do,  you【小题6】      (pay) 50. "The people sat like rocks while the man counted. When he reached 280, a large snake(蛇)【小题7】       (see) moving slowly from the table to the glass of milk. Mr Smith said,  "You 【小题8】     just       (show) us an example of self-control,  but how did you know there 【小题9】     (be) a snake in the room?""I 【小题10】       (not,  know) it was,  but I knew the milk was for the snake,  "the man answered. "It was lying right on my feet, " said Mrs Smith.