What are the rules of serving and receiving in tennis doubles? What are the grading rules?

Service order of doubles: At the beginning of the first game of each set, the server decides who will serve first, and at the beginning of the second game, the opponent also decides who will serve first. The third game was served by another server in the first game. The fourth game was served by another server in the second game. The following rounds serve in this order. The order of receiving the ball in doubles: The player who receives the ball first should decide who receives the ball first at the beginning of the first match, and continue to receive the ball first in this odd-numbered match. Both sides have to decide who will serve first at the beginning of the second set and continue to serve first in this draw. Their companions should take turns to accept the serve in each game. After receiving the serve, the two sides took turns to fight back. If the player touches the ball with his racket after his player hits the ball, the opponent is awarded a score.

Scoring rules: To sum up, the opponent will get 1 point in the following cases: when the server makes two consecutive service mistakes or foot mistakes. When the catcher hits the ball with his racket before the ball hits the ground, or when the ball touches his body and clothes. When the ball didn't get into the net before the second landing. When the return ball touches the ground, the fixed object or other objects are outside the boundary of the opponent's field. When the counterattack fails. The batter deliberately swatted or caught the ball with the ball in the game, or deliberately touched the ball with the racket many times.

In the "live ball", the player's body, racket (whether in his hand or not) or other articles he wears contact the net, net rod, singles rod, rope or wire rope, central belt, white cloth at the edge of the net or the ground in the opponent's court. Return a ball in the air that has not crossed the net. In addition to the racket held in the hand (whether it is one-handed or two-handed), the player's body or the items he wears will also touch the ball. When throwing a racket to hit the ball. During the game, the player deliberately changed the shape of the racket.

In any of the following circumstances, the opponent will be awarded a game: one point will be scored for each win, and the first four points will win a game. When both sides score 3 points, it is a draw. After the draw, a net win of two points is the victory of a game. If one side wins six games first, it wins one game, then the other side is awarded one game. When each side wins five games, one side wins one game.