Does time walk, or run, or fly?

My sister was just about done with preparation for some major exams. On a particular Sunday afternoon a couple of weeks before the testing period, she looked at the clock and whined "It's already four. How time flies!" My ever-busy wife, always hard-pressed for time but with her wits ever intact, remarked: "Yes, dear, my request to it to fly during weekdays and slow down to a walk, or better still to stop altogether at weekends, falls on deaf ears!"