单项选择题
Their government said that they had to use force to maintain social stability，but many people（）that it wouldn’t（）stability and harmony.
A.contradicted them by saying；makeB.countered by saying；make forC.opposed by saying；make upD.have been lagged behind；slip off
单项选择题 电力系统中一切不正常的相与相之间或相与地之间发生通路的情况称作（）。
单项选择题 若测得某稳压二极管的反向电流小于稳压管的最小工作电流，则该稳压管处于（）。
单项选择题 真空蒸馏所用的真空泵应安装（）。
