喹诺酮类抗菌药物的结构类型是
A．吡啶并嘧啶羧酸类
B．吡啶酮类
C．喹啉羧酸类
D．吡唑酮类
E．萘啶羧酸类
参考答案：A,C,E
—Nice to see you. I ________ you for a long time.
—I ________ in Beijing. I've just got back. [ ]
A. hadn't seen; was
B. haven't seen; shall be
C. haven't seen; was
D. didn't see; have been
在WindowsXP中，不能对任务进行的操作是（）。
A.改变尺寸大小
B.移动位置
C.删除
D.隐藏
