Look, this is my father. _____ he is a great father.[ ]

A. I think            

B. I thinks          

C. he thinks      

D. he think

体内各器官组织进行物质交换的主要媒介是______

A．脑脊液
B．血浆
C．组织间液
D．细胞内液
E．淋巴液