TN-S接零保护系统指的是什么？
参考答案：
具有专用保护零线的中性点直接接地的系统叫TN-S接零保护系统，俗称三相五线制系统。
—It is said that Mike fought with Tom in class.
—It ______ be him. It is not ______ him to have done it like that. [ ]
A. can't; like
B. may not; as
C. can't; as
D. mustn't; like
天疱疮患者血循环中自身抗体主要针对()
A．基底膜带
B．桥粒
C．半桥粒
D．真皮胶原纤维
