近年来痢疾杆菌较敏感的抗菌药物是（）
A.卡那霉素
B.庆大霉素
C.四环素
D.喹诺酮类
E.氨苄青霉素
参考答案：D
— Would you like to go and see the film with me this evening?
— I am sorry, I can't because I _____ my homework. [ ]
A. does
B. did
C. am doing
D. has done
什么是分布式多机操作系统？它有什么优缺点？
