利用电流的热效应可以清除高压输电线上的凌冰。若在正常供电时，_爱下问搜题

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问题选择题

利用电流的热效应可以清除高压输电线上的凌冰。若在正常供电时，高压输电电压为U，输电线上的热功率为△P；除冰时，输电线上的热功率需提高为9△P，设输电功率和输电线电阻不变．则除冰时输电电压应为

A．9U

B．3U

C．U/3

D．U/9

答案

答案：C

题目分析：设输电线电阻为r，高压线上的热耗功率：，若热耗功率变为，则：，联立可得：；输送功率不变，由，得：，C正确；

完形填空

Anne Spencer Morrow was born in 1906 in Englewood, New Jersey. She went to Smith College in Northampton, Massachusetts. She wanted to become a ______. She won two major prizes from the _____for her writing.
Anne Morrow was a quiet, shy and small young woman when she _____Charles Lindbergh in 1927. The 25-year- old man was tall and good-looking. Charles Lindbergh was one of __________ people in the world. He had just become the first person__________ a plane alone across the Atlantic Ocean, from New York to Paris. Two years __________, Anne and Charles Lindbergh were married. Reports about their__________ were on the front pages of newspapers.
After her marriage to Charles Lindbergh, Anne became a pilot too. She began _____many long airplane flights with her husband. The Lindberghs explored new ways to fly around the world. They seemed to enjoy the greatest _____ that any young people could not have.
Then in 1932, something______happened.They were in great sorrow (痛苦).The Lindberghs’ _____baby,twenty-month-old Charles, was kidnapped from their home in New Jersey. The body of the baby was discovered more than ten weeks later.
There were a huge number of reports about the case. Newspapers _____it "the Crime of the Century”. After the trial（审判）, the Lindberghs found it ______ to live in the United States. There were threats(威胁) on the life of their second child. And there were too _______ newspaper stories about them. So Anne and Charles Lindbergh moved to Europe in 1935. Four years later they moved _________ to the United States.
Anne Morrow Lindbergh never fully recovered from the death of her first child. Yet, she and her husband had five more children. She continued flying. In 1934, she became the first woman to win the National Geographic Society's Hubbard Gold Medal. She was honored for her exploration, research and discovery.

B．the most famous

C．the most careful

D．the most attractive

C．interesting

写作题

阅读下面的文字，按要求作文。

心态，即心理状态。一个人的心态很重要，一个幸运儿，如果心态不正常，可能身在福中不知福。一个命运坎坷的人，如果心态好，照样可以笑口常开。评价自己也要有个良好的心态。如果把自己看得过重，那就可能拒绝批评，陷入孤立；如果用一颗谨慎敬畏的心去对待周围的事，许多事情或许会迎刃而解。

根据以上材料，写一篇不少于800字的文章。立意自定，文体自选，标题自拟。