继电保护装置中定值的自动漂移有哪些？
参考答案：
（1）元器件老化及损坏。（2）温度与湿度的影响。（3）电源的影响。
Ⅶ.短文改错（每小题1.5分，共15分）
When tea and coffee were introduced to Europe in 18 th 1.
century, people thought they were harmful. But the King of 2.
Swede decided to find out whether it was true .It was 3.
happened that there had two brothers in prison 4.
at the time. The King ordered one of them drink tea 5.
every day and the other coffee. Both of them have lived 6.
many years with no problem. At the end the one who 7.
drink coffee every day died at the age of 83 and the 8.
other lived even long. Because of this, Swede is 9.
one of the countries which much tea and coffee are drunk today. 10.
《火力发电厂与变电站设计防火规范》规定，地下变电站楼梯间应设置（）防火门，并应向疏散方向方开启。
A.甲级
B.乙级
C.丙级
D.普通门
