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为什么随着反应堆运行时间的增加，必需要对一回路标准运行状态图进行修改？

答案

参考答案：

在辐射作用下，钢的脆性转变温度会上升，钢材吸收的快中子积分通量越多，脆性转变温度也升得越高，因此随着反应堆运行时间的增加，运行图的压力上部限制曲线朝高温区平移。为保证压力壳在运行寿期末安全运行，可能要对一回路标准状态压力与温度运行图进行修改

单项选择题 A1型题

荧光原位杂交技术主要应用于（）

A.免疫表型分析

B.DNA含量分析

C.非二倍体细胞定量分析

D.细胞增殖活性分析

E.基因诊断、基因定位和基因作图
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阅读理解

What is eBay? The simple answer is that it is a global trading platform where nearly anyone can trade practically anything. People can sell and buy all kinds of products and goods, including cars, movies and DVDs, sporting goods, travel tickets, musical instruments, clothes and shoes — the list goes on and on 

The idea came from Peter Omidyar, who was born in Paris and moved to Washington when he was still a child. At high school, he became very interested in computer programming and after graduating from Tuft University in 1988, he worked for the next few years as a computer engineer. In his free time he started Bay as a kind of hobby, at first offering the service free by word of mouth. By 1996 there was so much traffic on the website that he had to upgrade (升级) and he began charging a fee to members. Joined by a friend, Peter Skill, and in 1998 by his capable CEO, Meg Whitman, he has never looked back. Even in the great crashes of the late 1990s, ebay has gone from strength to strength. It is now one of the ten most visited online shopping websites on the Internet 

Ebay sells connections, not goods, putting buyer and seller into contact with each other. All you have to do is lake an e-photo, write a description, fill out a sales form and you are in business.  The world is your market place. Of course for each item, eBay gets a percentage and that is a great deal of money. Every day there are more than sixteen million items listed on eBay and eighty percent of the items are sold.

42. We learn from the text that eBay provides people with _________.

A. a way of buying and selling goods 

B. a place to show their own photos

C. a website for them to upgrade

D. a chance to buy things at low prices 

43. Why did Peter create eBay after graduating from university? 

A. For fun                                     B. To make money 

C. For gathering the engineers                            D. To fulfill a task of his company 

44. From “he has never looked back” in Paragraph 2 we learn that Peter _________.

A. did not feel lonely                             B. was always hopeful 

C. did not think about the past                             D. became more and more successful 

45. How does eBay make money from its website? 

A. By bringing sellers together.                             B. By charging for each sale 

C. By listing items online                             D. By making e-photos.  
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