阻尼量为临界值的（）称之为检波器的开路阻尼。
A、0.1-0.2
B、0.2-0.3
C、0.25-0.35
D、0.35-0.4
参考答案：C
— _____ are these?
— They are cows. [ ]
A. Which
B. Who
C. What
道德义务与道德情感，是（）的。
