What are the technical essentials of tennis starting serve?

I started serving, thinking that I was also a good cook, and took out my own things to attract jade. The following are several powerful starting services I developed and used, and I have applied for the patent trademark "Two-beat Card Starting Service". If there are similarities, they are all fakes! 1, ping-pong backspin. It's a bit like table tennis to serve the ball under the hand. At shoulder height, it is difficult for the ball to be thrown up, with a strong downward spin or lateral downward spin. The highest state is that the ball just jumps out of the doubles sideline or jumps back to the net. Because it is smaller than the overhand serve, it leaves less preparation time for the opponent and it is difficult to catch up. I often use it in the game, and I can serve a good side spin with a strong serve. If my opponent stands close to the net, I will serve hard. If my opponent retreats, I will use ping-pong backspin. The opponent just barely returns the ball and will lose his position. The overall effect is a bit like WJ's side spin serve, but it is more rotary. Because table tennis backspin is flush with the eyes, it is more accurate and easier to hit the ball, especially suitable for friends with table tennis foundation. Of course, table tennis backspin can have the same throwing and beating actions as ordinary overhand serve, which is more concealed. This is a practical service between the upper hand and the lower hand. 2. Reverse rotation. The side spin of the overhand serve is the right side of the ball, and the underhand serve can hit the left side of the ball, resulting in the opposite rotation. Suddenly, opponents often don't adapt. Treatment 3. 0 players are still quite practical, but against 4. 0 and above players have no influence. An overhand serve, a feint, and then an underhand serve. This smacks of deception. The opponent thinks that your pitch is not good, so you will catch it before serving. I didn't expect you to hit the ball with your hand suddenly when the ball was about to land. Even if what you are talking about is a vegetable ball, it may be a disastrous blow to an opponent who has just relaxed and is ready to relax. It's not just scores that hurt opponents, but also psychology. I used it once at school, especially in a college competition. It was a preemptive game at that time. I scored a key point when I served the ball. But it also alarmed the referee at that time, because this is really controversial. Later, this trick was practiced to perfection. At the key point in the left area, I will make a fake action of killing my opponent with too much force, and the racket will be thrown to the left rear of my body. Then, when the opponent was dumbfounded, he put a small ball with his backhand when the ball was about to land. This used to be my secret weapon. Now I'll share it with you. Because tennis is no longer the fun for me to win by playing sideline, haha.