1. The machine must break down at this busy hour.

2. Una1987Zheng: The machine broke down at this busy hour.

3. It is usually expressed as the traffic volume during the highest one-hour period of the day (Busy Hour).

4. Busy Hour call Attempt (BHCA) is the number of times a telephone call is attempted during the busiest hour of the day.

5. I make some impatience on the condition of heavy work and busy hour.