They ______ his claim of innocence with eyewitness testimony.

A．it can reflect the development of the nation
B．it can demonstrate the nation's civilization
C．it helps understand the nation's past and present
D．it helps produce new cultural tools and technology

A．it is the printed version of standardized folk music
B．it encourages people to popularize printed versions of songs
C．it tends to standardize folk songs when it is used by folk musicians
D．it has a great effect on the music-culture as more and more people are able to read it