By using MP3, a 600M-byte music CD can be

问题：

By using MP3, a 600M-byte music CD can be (70) to 50M bytes or less. It can be streamed (downloaded in chunks)so that you can begin listening to the opening bars while the (71) of the file arrives in the background. And, most important, MP3 music files retain good listening (72) that (73) compression schemes lacked. That (74) of features makes accessing and distributing music on the Web practical for the first time.

A．add

B．combination

C．difference

D．condition