变压器系_________、________跳闸,在未查明原因和消除故障之前,不得送电
参考答案:瓦斯,差动保护动作
He has worked in the city _______ three years ago while his wife has been here______only one month.
A.since , for
B.since, since
C.for, since
D.for, since
目前,我国通过证券交易所进行的证券交易均采用( )方式。
A.书面报价 B.电脑报价 C.口头报价 D.传真报价