The networking standard works at two levels: the physical level and the protocol level.
查看答案
Bluetooth is wireless and automatic, but expensive.
A. 对
B. 错
Infrared is also a wireless connection as Bluetooth.
A. 对
B. 错
Infrared is a kind of automatic connection.
A. 对
B. 错
The two drawbacks of infrared communications are actually advantageous in some regards .
A. 对
B. 错
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