フリー問題

問題文

One blank waits for the packet that the keeper in the middle sends back when one side asks to take one named stream; the next waits for the message that asks the far side to say it arrived. Which option fits both?

選択肢

1. The word list names the PUBACK packet that the keeper in the middle sends back when one side asks to take one named stream, and the CON message that asks the far side to say it arrived.
2. The word list names the SUBACK packet that the keeper in the middle sends back when one side asks to take one named stream, and the NON message that asks the far side to say it arrived.
3. The word list names the SUBACK packet that the keeper in the middle sends back when one side asks to take one named stream, and the CON message that asks the far side to say it arrived.
4. The word list names the PUBACK packet that the keeper in the middle sends back when one side asks to take one named stream, and the NON message that asks the far side to say it arrived.