题干

关于电阻的计算式和决定式,下面说法正确的是    

A:导体的电阻与其两端电压成正比,与电流成反比

B:导体的电阻仅与导体长度、横截面积和材料有关

C:导体的电阻不随工作温度变化而变化

D:对一段一定的导体来说,恒温下比值是恒定的,导体电阻不随U或I的变化而变化

上一题 下一题 0.0难度 选择题 更新时间:2019-05-25 02:08:59

答案(点此获取答案解析)

D

同类题2

阅读理解

(C)

    Walter Dean Myers,born on August 12,1937,was an American writer of children's books.He was known for young adult literature (文学) He wrote more than 100 books,including picture books and non﹣fiction."I care about writing for young people because I remember how much I needed help and guidance at that time in my life,"Myers said in his book.

    Myers loved writing.He got up at five o'clock every morning.He worked at home in a small office that used to be his son's bedroom.

    Myers would first write an outline for every book.He called this prewriting.He imagined what the story would be and wrote down ideas in a notebook.To make sure there's enough action and dialogue for a good story,he thought of 30scenes.He wrote a short description of each scene in his notebook.

    He also cut out pictures of real people and put them on his office walls.He looked at those pictures and came up with ideas.Once he knew what the story would be and who the characters were,he began to write the book.He wrote five pages a day on his computer.

    Myers usually worked on three books at a time.When he was not prewriting or writing a book,he might be rewriting something he had already completed.Then he would send the story to his agent (经纪人).He or she made suggestions for the story.After these final changes were made,the book was published and made its way to bookstores and libraries.By that time,Myers would begin to write his next book."I want to do the best that I can with my writing."said Myers.