If you want to take the postgraduate entrance examination, you have no tennis foundation, and you can only focus on referees and theoretical knowledge. If you still want to improve your technology, it will be particularly hard. It's hard to practice tennis in the sun every day. I graduated from tennis, and the technical aspects of graduate students are similar to ours. There is a tennis passing competition every semester to test the level of tennis players. Postgraduate entrance examination is probably forehand and backhand stroke, overhand serve, volley ball, high pressure ball, footwork and explosive force test. There may be some subtle differences, but since you don't have a tennis foundation, I recommend you to develop into referee and theoretical knowledge, which is easier.