变电设备新建时,可以选择的设备状态是()或()。
A.未投运、在运
B.停运、在运
C.停运、未投运
D.投运、未在运
参考答案:A
John had made up his mind to give it up, but on _________ second thought he determined to have __________ third try.
A./ ; /
B. a; a
C.the; a
D./ ; a
钢中P元素会引起钢的()。
A.热脆
B.冷脆
C.冷热脆