问题 实验题

(10分)某同学要描绘半导体二极管的电流I与正向电压U的关系图象,利用如图所示电路做实验,得到的U和I的实验数据见下表:

(1)在闭合电键S前,变阻器的滑动片应移至    (选填“左端”或“右端”)。

(2)当时,对电压起粗调作用的是          (选填“”或“”)。

(3)在坐标纸中画出二极管的电流I与正向电压U的关系图象。

(4)将上述的二极管接入如右图所示电路中,已知电源电动势 E=9V、内阻不计,电阻R1=2kΩ,则二极管D消耗的电功率为       W。

答案

(1)右端       (2分)

(2)R1             (2分)

(3)如图所示   (3分)

(4)) (3分)

(1)在闭合电键S前,变阻器的阻值应调到最大

(2)大的滑动变阻器起到粗调的作用

(3)略

(4)把R1归到电源内阻,二极管两端的电压即为路端电压,画出路端电压和电流的关系图像(与横坐标的交点为电源电动势,与横坐标的交点为短路电流E/R 1),曲线和直线的交点就是此时二极管的工作电压和电流

阅读理解

A letter of reply is sometimes a most treasured thing. Here is a story that tells about this common and natural human sentiment

The busiest woman in Labrador during one bitter cold Christmas not very long ago, was an Australian nurse by the naI11e of Kate Austen. But Nurse Austen was not too busy to acknowledge with a long, friendly letter every gift of food or clothing received for distribution to the natives in that cold and poor district of the north. Among the gifts was a box of knittings for children, knitted(编织)and sent by a woman in Toronto.

Nurse Austen was busy, exhausted and not feeling too well that winter.She could have written just ordinary routine notes of acknowledgement. But that was not her way. She sat down and wrote the woman in Toronto a real letter telling all about the village, and the names of the children who were wearing the knitted gloves and caps, and what they said -when they got them, and how they looked when they wore them.She wanted the woman who had knitted and sent all those lovely knittings "to see how much happiness and warmth she had created." Not long after, she received the following answer from Canada.

Dear Miss Austen:

Your letter made me happy. I did not expect such a full return. I am eighty years old, and I am blind. There is little I can do except knit, and that is why I knit so many caps and sweaters and scarves.Of course I cannot write this, so my daughter-in-law is doing it for me.She also sewed the seams and made the buttonholes for the knitted things.

I know something of the work you are doing. At the age of nineteen I married a man who was going to China to be a missionary(传教士). For forty years, with an occasional year at home in America, we Worked in China, and during that time our two sons and a daughter were born to us, of whom only one son survives.\After forty years, my husband's health began to fail. We returned to the States where he took charge of a settlement house in Brooklyn, New York. A surprising number of the problems we faced there were similar to the problems we had met in China.When my husband died, I came to Toronto to live with my son and daughter-in-law. They are very good to me, and I pride myself that I am little trouble to them, though it is hard for a blind old lady to be sure of anything.

What I most want to say, my dear, is this. For sixty years I have been making up missionary packages of such clothing or food or medicine or books as I could collect. In various parts of the world and to various parts of the world I have sent them.Sometimes I have received a printed note of acknowledgement from the headquarters depot or mission board, sometimes nothing.Occasionally I :have been informed that my contribution was planned for Syria or Armenia or the upper Yangtze. But never before in all that time have l had a personal letter picturing the village and telling me who is wearing the clothing and what they said.I did not suppose that ever in my lifetime I should receive a letter like that.

May God bless you.

Sincerely yours,

小题1:The underlined word “sentiment”(in Paragraph l) most probably means“       ”?

A.view point

B.gentle feeling

C.way of thinking

D.expression of attitude小题2:The underlined sentence “But that was not her way” (in Paragraph 3) implies that          

A.she would not just write an ordinary letter of thanks

B.she was too busy to write a note of acknowledgement

C.she was not busy, exhaustec3 0r feeling too well that time

D.she wrote a letter telling all about the village and the children小题3:Why was Laura so happy when she received the letter from Miss Austen? Because      

A.the letter was* from an Australian nurse

B.she was already eighty years old and blind

C.she had never received a letter like that

D.the letter was not supposed to reach her小题4:Ms. Laura N. Russell is now living in       

A.China

B.Australia

C.Canada

D.the States小题5:For decades, Ms. Laura has been to       and sent contributions to people all over the world.

A.Toronto and New York only

B.Syria and Armenia once

C.the upper Yangtze area alone

D.many places of the world

问答题 简答题