能同时兴奋α和β受体的药物是（）。
A.多巴胺
B.去甲肾上腺素
C.肾上腺素
D.麻黄碱
E.异丙肾上腺素
参考答案：C
—Thank you for your letter.
—_____. [ ]
A. It doesn't matter.
B. It's funny
C. You are interesting
D. You're welcome
锥形除渣器用什么原理分离杂质？
