血清镁离子浓度达到多少可出现呼吸抑制

A．不完全流产
B．稽留流产
C．难免流产
D．先兆流产
E．完全流产

Computer （）is a complex consisting of two or more connected computing units，it is used for the purpose of data communication and resource sharing.

A．storage

B．device

C．network

D．processor