正確答案：AD
解析：Explanation:
A single device could not be sending a frame. and receiving a frame. at the same time because it would mean that a collision was occurring. So, devices simply chose not to send a frame. while receiving a frame. That logic is called half-duplex logic.

Ethernet switches allow multiple frames to be sent over different ports at the same time. Additionally, if only one device is connected to a switch port, there is never a possibility that a collision could occur. So, LAN switches with only one device cabled to each port of the switch allow the use of full-duplex operation. Full duplex means that an Ethernet card can send and receive concurrently.

Incorrect Answers:
B. Full duplex effectively doubles the throughput of half-duplex operation, because data can be both sent and received at the full 10/100 speed.

C, E. In half duplex operation, the network is shared between all devices in the collision domain.