Definition of walk: If you move the ball beyond the allowable range, you should walk. The rules stipulate that you should fly to catch the ball, and the first foot to land should be the center foot. Both feet should land at the same time, and both feet can be the center foot (the foot that moves later is the center foot). You can pass the ball and shoot when you lift the center foot, but you can't dribble. When you lift your center foot, you can't land until the ball leaves your hand. When dribbling begins, the ball must leave first.

(1) At the moment when the ball is stopped after dribbling, A foot lands and B foot volleys, which foot is the center foot?

A: Foot A is the center foot.

(2) After the dribbling stops (for a period of time), the center foot A does not move, and the other foot B dives forward, then A leaves the ground and B takes off and shoots hard. Do you want to walk?

A: If A leaves the ground and doesn't touch it again, it won't go.

(3) When a right-handed player makes a three-step layup, he probes the ball with his left foot, dribbles the ball with his hand, then stops the ball in his hand and completes the three-step layup. Pay attention to the hard jump of the last left foot. Which foot is the center foot and when was it determined?

A: The center foot is determined by the position of the two feet at the end of dribbling and receiving the ball. This problem should be walking, because in the end, if you want to take off with your left foot, you must take your right foot as the center foot, and the right-handed player touches the left foot to dribble at the same time, and then complete the three-step layup. This is impossible unless his action is not a three-step layup or he walks. The reason for this is the following：

Hypothesis (1): When he stops the ball, his left foot touches the ground and his right foot is suspended. At this time, his left foot is the center foot, and it is impossible to complete the above actions unless he walks.

Hypothesis (2): After stopping the ball, both feet touch the ground, and then the foot that leaves the ground is the center foot. If he wants to complete a three-step layup with his left foot and can only take his right foot as the center, then he should lift his left foot first, but he can only take off with his right foot first, which is contradictory and exclusive (unless he walks or the action is not a three-step layup).

So he must have left.