CPCR是一个多环节的连续过程。目前国际上通行的办法是把CPCR划分为( )个阶段
A.5B.6C.3D.4E.2
参考答案:C
I’m very lonely .I’d like to find someone
A. to play
B. playing
C. to play with
D.playing with
离心泵在安装时,必须保证泵轴与电动机轴的同心度。