多项选择题Which of the following are the duties of a receptionist? A、providing check-in and checkout services to guests B、answering any questions from the guests C、handling complaints from unsatisfied guests D、taking messages for the guests
单项选择题机体内能直接产生抗体的细胞是 A、浆细胞 B、T细胞 C、B细胞 D、NK细胞
