[判断题]经单位批准，可在带有压力（液体压力或气体压力）的设备上或带电的设备上进行焊接。

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`]

爆炸，生物质可分为以下3类：
①I类：矿井甲烷；
②II类：爆炸性气体混合物（含蒸气、薄雾）；
③III类：爆炸性粉尘（含纤维）。