问题 阅读理解

阅读理解,判断对(T)错(F)。

      Mr. Green has a dog. It loves him very much. One day Mr. Green goes out to throw away his old shoes. He

puts them near the rubbish box. 

      The dog goes there to look for food. It sees the shoes. It knows they are its owner's shoes. So the dog takes

one shoe back with its mouth, then the other. The dog puts them near his bed. He is sleeping. 

      After some time, Mr. Green gets up. He sees the shoes. He is angry. He lights a fire (点火) and throws them

into the fire. Just then there is a big wind. The fire lights the house. But the dog takes the shoes out of the fire

again at last.

( ) 1. Mr. Green's dog loves him very much.

( ) 2. The dog takes back the shoes with its mouth.

( ) 3. The house is on fire when Mr. Green is sleeping.

( ) 4. Mr. Green is not happy when the dog takes the shoes back home.

( ) 5. The dog goes to the rubbish box to look for his owner's shoes one day.

答案

1. T  2. T  3. F  4. T  5. F

实验题

小静同学在用电流表、电压表测小灯泡的电阻、电功率的实验时,灯泡上标有“2.5V” 字样。

(1)如图所示,小静连接的电路还没有完成,如果要求滑动变阻器的滑片P 向右移动时,电流表的示数变大,导线M应与滑动变阻器的接线柱     连接(填“A ”、“B”或“D”)。

(2)电路连接正确后,小静闭合开关,发现小灯泡不亮,电压表无示数,电流表有示数,则产生这个故障的原因可能是                   

(3)排除故障后进行实验,实验中测得灯泡两端电压、通过的电流、灯丝的电阻、灯泡的电功率和观察到的灯泡发光情况等,并记入下表:

实验次数电压U/V电流I/A电阻R/Ω电功率P/W发光情况
11.50.226.80.33较暗
22.00.26 0.52较亮
32.5 8.3 正常发光
根据以上观察到的现象和记录的实验数据。

①你认为小灯泡L的额定功率为___________ (保留二位小数) 。

②小灯泡L在通过电流为0.26A时其电阻值为____________ (保留一位小数)。

③从以上表格中你能得出小灯泡的亮度由                          决定。

(4)他们还注意到,灯丝的电阻值随电压升高而增大,同学们想:导体的电阻不是与电压、电流无关吗?怎么会有这样的结论呢?你认为他们说的有道理吗?请你给他们作出合理的解释:                                         。                                                                                                                                          

单项选择题