John's success has nothing to do with good luck. It is years of hard work _____ has made him what he is today. [ ]

A. why

B. when

C. which

D. that

源程序的文档化不包括( )。

A．符号名的命名要有实际意义

B．正确的文档形式

C．良好的视觉组织

D．正确的程序注释