以下免疫器官中属于周围免疫器官的是()
A.脾脏
B.法氏囊
C.淋巴结
D.黏膜免疫系统
E.骨髓
参考答案:A, C, D
—How about singing songs with me?
—I’m sorry I can’t. I help my father with his work. [ ]
A. have to
B. can
C. may
购买力平价理论的两种形式为()和()。