高速冷冻离心机安全保护装置包括()
A.主电源过电流保护装置
B.驱动回路超速保护
C.冷冻机超负荷保护
D.操作安全保护
E.全封闭保护系统
参考答案:A, B, C, D
氧在焊缝金属中存在的形式主要是( )夹杂物。
A.FeO
B.SiO
C.MnO
D.CuO
This air crash which was suspected to be plotted by international political terrorists led to the stop of the diplomatic relations between the two countries.
A.suspensory
B.sustenance
C.suspicion
D.suspension