—Is this his dictionary?
—Yes,_____ _____. [ ]
A. it am
B. it is
C. it isn't
D. it's
把200本书按5:3分给甲、乙两个班,甲班分得______本.
氯霉素具有下列哪些理化性质( )。
A.性质稳定,耐热
B.水溶液煮沸5小时对抗菌活性无影响
C.在强碱强酸条件下可水解
D.具有羟肟酸铁颜色反应
E.具有旋光性