参与神经-骨骼肌接头处终板电位产生的是
A．化学门控通道B．电压门控通道C．机械门控通道D．G蛋白耦联受体
参考答案：A
Mr Brown is outgoing (外向的). He has _____ friends. [ ]
A. many China
B. much China
C. many Chinese
D. much Chinese
如一风支管仅有一个百叶风口，且设于风管末端，风口风速上限值低于风管风速上限值，此时接风口时是加变径还是将整个风管加粗？
