The general said to the men, "Don't stop practicing. The general _______ the man ________.  [ ]

A. ordered; not to stop          

B. ordered; don't stop  

C. said to; not to stop            

D. requested; to not stop

设U是所有属性的集合，X、Y、Z都是U的子集，且Z=U—X—Y。下面关于多值依赖 的叙述中，______是不正确的。

A．若X→→Y，则X→→Z

B．若X→Y，则X→→Y

C．若X→→Y，且Y’ Y，则X→→Y’

D．若Z=Ф，则X→→Y