变压器在绝缘电阻测试()要对地放电。
A.前
B.后
C.中间
D.前和后
参考答案:D
Only after Mary read her composition the second time________the spelling mistake.
(2012·天津,6)
A.did she notice
B.she noticed
C.does she notice
D.she has noticed
辨析题:高炉各部冷却器达到的水压要求等于或大于炉内压力。