9个数字2个一组能组成多少组

简介：There were several people in white coats standing outside. The leader was a fat middle-aged man wearing glasses and with slightly bald hair. When he saw Li Tiancheng, he stepped forward with a smile on his face and stretched out his hand: Secretary Li. Chief, hello hello! My name is Wang Guosen, and I am the vice president of our hospital. That Dean Li went to Yanjing for a meeting and was not in the hospital.