7-5-2c A1 throws a forward pass to A2 who throws second to A3. The pass by A2 is an illegal pass.
7-5-2c A1 throws a pass to A2 who is beyond the line of scrimmage. A2 retreats behind the line of scrimmage and then throws a pass to A3. The pass by A2 is an illegal pass as only one forward pass be thrown.