In the afternoon of December 28, 2019, all the members of DDTS from all over the country and even all over the world rushed to Nanjing to attend the annual feast. This is an unusual gathering. On the occasion of farewelling to the old and welcoming the new, DDTS had her 15th birthday. Over the past 15 years, we have witnessed brilliance occasion and went through storm together. In the future, we will continue to work together to compose a new chapter.