离心式压缩机设立压缩机自循环回路的目的是（）。
A、防止共振
B、防止喘振
C、防止气蚀
D、防止低流量时气体温度升高而损坏压缩机
参考答案：B
It's reported that 289 more trains were added____ passengers on Sunday to meet the needs of
those______ home for the Spring Festival. [ ]
A. to take; returning
B. taking; returning
C. taken; to retum
D. take; returned
下列各项资金成本中，属于资金占用费的是( )。
A．企业股票发行费 B．企业债券发行费C．支付股东的股利 D．企业内部活动费
