氯气离心式压缩机采用（）这类轴承具有安全可靠、运行稳定、抗震性好、使用寿命长等优点。
A.静压轴承
B.动压轴承
C.滑动轴承
D.滚动轴承
参考答案：B
People were afraid to leave their house, ______ the police had been ordered to stand by in case, of emergency, they were just as confused and helpless as anybody else.
A．and even if
B．but since
C．however after
D．for though
在垄断资本主义阶段占统治地位的资本是( )。
A．工业资本 B．农业资本C．银行资本 D．金融资本
