某受体被激动后，引起支气管平滑肌松弛，此受体为
A.α受体
B.β1受体
C.β2受体
D.M受体
E.N2受体
参考答案：C
Tom often _____ TV on weekends. Today is Sunday. He _____ TV now.[ ]
A. watch, is watching
B. watches, is watching
C. watches, watching
D. watches, watches
什么是冻雨？
