Discuss the rule of service in doubles.

Rule of service in doubles (badminton): 1. The server serves from the right service court at the start and when the score is even, and from the left when the score is odd. 2. The serve is made diagonally to the opposite service court, and only the receiver may return it. 3. The side that wins the rally scores a point and the server serves again, changing service courts. 4. When the serving side loses a rally, the service passes to the opponents. 5. Players do not change positions except when serving or receiving; partners do not serve in order after the point is won.