问题 问答题 论述题

选择锚段长度应综合考虑哪些因素?

答案

参考答案:

(1)气象因素,如最高温度,最低温度,吊弦、定位器和腕臂处于最佳位置时的温度,最大风速,覆冰厚度;

(2)补偿张力的大小及导线张力差;

(3)接触线在定位点的纵向位移和横向位移;纵向位移使线夹两边产生张力差,使线夹承受较大的剪切应力;横向位移使接触线拉出值产生变化;

(4)补偿装置的结构形式、有效工作范围和补偿效率;

(5)导线的架设高度、抗拉强度、弹性系数和截面积;

(6)锚段关节的结构形式,两悬挂间的空气绝缘间隙及其所允许的偏移值;

(7)线路条件。

阅读理解

Barak Obama(巴拉克.奥巴马), a black man, is the president(总统) of the United States now. He was born on August 4th, 1961, in Hawaii(夏威夷) and has lived in many places. His mother was from Kansas(堪萨斯州) and his father was from Kenya(肯尼亚). Obama went to Columbia University(哥伦比亚大学) in New York and got a law degree(律师学位) at Harvard University(哈佛大学) in Massachusetts(马萨诸塞州). His wife is Michelle Obama(米歇尔.奥巴马). She also worked as a lawyer and later worked for the University of Chicago(芝加哥大学). They have two young daughters.

Obama wrote a book Dreams from My Father.  “ I always live in the dream of my father and American people, ” Obama once said. He was born in a poor family. And his grandparents looked after him very well when Obama was young. He also lived and worked in Africa(非洲). Then he got good education(教育) in Harvard University. On November 4th, 2008, he became the new president of America for the next four years.

根据短文内容,选择最佳答案,并在答题卷上按要求作答。

小题1:Where was Barack Obama born?

A.In Kansas.

B.In Hawaii.

C.In Kenya.

D.In Massachusetts.小题2:How many universities are there in the passage?

A.Three .

B.Six.

C.Two.

D.Five.小题3:Barack Obama became President at the age of           

A.37.

B.57.

C.40.

D.47.小题4:Which of the following is NOT true?

A.Obama’s father was born in Kenya.

B.Obama has a son and a daughter.

C.Obama once worked in Africa.

D.Obama got good education in Harvard University.小题5:Which is the best title of this passage?

A.Education of a President

B.Dreams from My father

C.Life of Barack Obama

D.Barack Obama and His Wife

多项选择题