B passes the ball to C, who slowly runs diagonally forward against the center.
When B has passed the ball, B runs quickly in front of C.
C passes the ball to A, who runs slowly diagonally forward against the center.
After the passing C runs quickly in front of A, who passes to B and runs in front.......

The rear lines of a badminton court can be used in order not to crowd the game.
When a player reaches the back line the running direction is changed, so it becomes diagonally forward against the center. When a player reaches the back line the running direction is changed, so it becomes diagonally forward against the middle.