从下列被监控量选择哪一个属于DO量（）。
A.交流电压
B.门磁告警
C.烟感复位
参考答案：C
— Time files! The fantastic holiday is over. We'll have to part.
— No need to feel blue.______ [ ]
A . Impossible is nothing
B. A single flower does not make a spring
C. All that glitters is not gold
D. All good things come to an end.
为什么α受体阻断药能使肾上腺素的升压作用翻转，却不能使去甲肾上腺素的升压作用翻转？
to feel blue.______ [ ]