_______________是指数据库的物理结构改变时，尽量不影响整体逻辑结构及应用程序。
参考答案：物理数据独立性
China has got a good ________ for fighting against the flu with its careful and smooth organization.[ ]
A. reputation
B. influence
C. impression
D. knowledge
There goes the bell. Hurry up, _______you’ll be late for class.
A．and
B．or
C．so
D．but
