问题 单项选择题

电线是由多股单线绞制而成,受力后会产生塑性伸长和蠕变(简称初伸长),它与拉力的大小和时间有关。在运行中,这种初伸长逐渐放出,使弧垂增大,减小了安全距离,所以在架线施工中,需预先补偿,即适当减小施工弧垂,使初伸长放出后达到设计预期弧垂。

镀锌钢绞线的初伸长约1/万,若用降温法补偿,其值为( )。

A.5℃;
B.10℃;
C.15℃;
D.20℃。

答案

参考答案:B

解析: 根据DL/T 5092-1999中7.06条规定。

阅读理解

A young man called Jack has visited many countries. He knows few foreign languages, but he can always find someone who knows enough English to understand what he says. Last summer he went to China. He enjoyed himself in China and liked Chinese food very much.

One day he went into a restaurant in a small village. He knew the Chinese word ‘rice’, so he ordered some rice. The village was famous for its mushrooms, and Jack thought they must be very fresh and delicious. He asked the waiter in English. However, the waiter couldn’t understand at all, so he could do nothing for Jack. Jack thought hard. When he saw a piece of paper on the table, he had a good idea. He took out a pencil and drew a picture of a mushroom carefully. The waiter looked at the picture for a long time, then he smiled and left. A few minutes later, he came back with a black umbrella in his hand.

小题1:What does ‘mushrooms’ mean? 

A.洋葱

B.花菜

C.洋伞

D.蘑菇小题2:The waiter didn’t help Jack because _____________.

A.he had no mushrooms in the kitchen

B.he disliked the mushrooms

C.he didn’t know English well

D.he thought the mushrooms were poisonous小题3:Jack asked the waiter for ___________.

A.a pencil

B.a picture

C.an umbrella

D.some mushrooms小题4:The waiter smiled because __________.

A.the picture was beautiful

B.he was very happy

C.Jack gave a gift to him

D.he thought he understood Jack小题5:At last the waiter came back with an umbrella, because _______.   

A.it is raining outside

B.it is going to rain

C.the mushroom Jack drew looked like an umbrella

D.Jack was good at drawing

单项选择题