[判断题]竖向管道安装按图纸要求检查确认各层预留孔洞、预埋套管的坐标、标高。 (　　)
A.正确
B.错误

Definition: 
Action potential is a rapid, reversible, and conductive change of the membrane potential after the cell is stimulated. [2.5`]
Forming mechanisms: 
(1) Reduction in membrane potential (depolarization) to "threshold" level leads to opening of Na+ channels, allowing Na+ to enter the cell. [1.5`]
(2) Interior becomes positive, reversed polarization [1.5`]
(3) The Na+ channels then close automatically followed by a period of inactivation. [1.5`]
(4) Next K+ channels open, K+ leaves the cell and the interior again becomes negative (repolarization). [1.5`]
(5) Na+- K+ ATPase serves as a pump to recover normal ionic distribution in or out the membrane. [1.5`]