离心泵轴承箱发热原因是()。
A、机械密封损坏
B、润滑油过少或太脏
C、转速过低
D、泵体内部动静部件产生碰擦
参考答案:B
I __________ glasses since I was in primary school and I hate them. They make me look
like a bookworm. [ ]
A. have worn
B. have been wearing
C. have been worn
D. was wearing
企业退休人员实行社会化管理服务,其养老金要实行()发放
A.货币化
B.电子化
C.统一化
D.社会化