罗马人向埃特鲁里亚人学习了下面哪两种技术？（）

A、混凝土技术；拱券技术

B、混凝土技术；雕刻技术

C、拱券技术；雕刻技术

D、拱券技术；磨具制造技术

MIDI enables people to use (61) computers and electronic musical instruments. There are actually three components to M1DI, the communications " (62) ", the Hardware Interface and a distribution (63) called "Standard MIDI Files". In the context of the WWW, the most interesting component is the (64) Format. In principle, MIDI files contain sequences of MIDI Protocol messages. However, when MIDI Protocol (65) are stored in MID! files, the events are also time-stamped for playback in the proper sequence. Music delivered by MIDI files is the most common use of MIDI today.

A．messages

B．packets

C．frame

D．information