If you use one sentence to describe the life that people come and go in a hurry, it would be: some people do not belong to you, but it is good to meet them.
Everyone's life is not like a textbook-like story. You can always see the ending after reading the beginning. Real life is always pushed forward by the torrent of fate, with ups and downs, surrounded by threads. The ending may be happy or sad. In the end, you don't know where the ending of a life is, but it is often your own duty to look back and not be afraid of the unknown ahead. Only then will life be colorful and live up to the hundred years life has given us.