题目

接种卡介苗可以有效预防结核病，其原因是( ) A . 卡介苗在人体内能激活人体的吞噬细胞，将结核杆菌吞噬了 B . 接种卡介苗后能使人在不发病的情况下，产生抵抗结核杆菌的抗体 C . 卡介苗能提高人体的各项生理活动，增强抵抗力 D . 卡介苗进入人体后能直接消灭侵入人体内的结核杆菌 答案：BThere are two _____ students in my school. But our school  _____ library. [     ]A. hundreds, doesn't have a B. hundred, doesn't have a C. hundreds of, doesn't have any D. hundred, doesn't have any