六个数字有多少种组合两位数

简介：The long-haired girl's name was Xiao Shanshan. She was in the same junior high school as Xie Ningtian, but in a different class. Xie Ningtian was not very familiar with her. Although she was a little dissatisfied with Xiao Shanshan's behavior, she didn't say it out loud for the sake of face.