题目

The one _________ me is writing on the blackboard ________ the classroom  A. behind ; in front of                              B. behind; in the front ofC. at the back of; in front of                     D. at the back of ; in the front of 答案：B观察细胞内某生理过程示意图(图中甲表示甲硫氨酸，丙表示丙氨酸)，分析下列细胞中不能发生图示生理过程的是 A．人体成熟的红细胞   B．大肠杆菌细胞     C．浆细胞    D．根毛细胞