Being admitted to Tsinghua at the age of 28 is a great achievement! Tsinghua University is one of the top universities in China, with excellent teachers and academic resources. You will have the opportunity to receive world-class education and training by attending undergraduate courses in Tsinghua University, which will lay a solid foundation for your future development.
Although age may have some influence on considering career development and employment, it doesn't mean that you have no future. In today's society, people pay more and more attention to personal ability and actual performance, not just age. But you can still succeed in your field by studying hard and constantly improving your ability. It is important to keep a positive attitude, keep studying and working hard, give full play to one's own advantages, and make use of the acquired knowledge and skills to make contributions to society.