Two-way transports can send and receive messages using the same channel.
双向传输可以使用同一个通道发送和接收消息。
2
Thus, distinguishes between two kinds of battery electrolyte "fixed" way and provide oxygen to the cathode channel differently, thus the performance of the two kinds of battery also.
One way is what is called two-channel authentication, using something other than the computer - most likely a cellphone - as part of the log-on procedure.