Relations between the two countries have______ since the agreement was signed.

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．Folk songs cannot be spread far unless they are printed on music sheets.
B．Music cannot be passed on to the future generations unless it is recorded.
C．The development of music culture is highly dependent on its material aspect.
D．Musical instruments developed through the years will sooner or later be replaced by computers.