题目

Your computer has been playing music for years, one CD at a time.  Now hundreds of songs can be stored in your PC if they' re in the MP3 format (格式). What is it? MP3 compressed(压缩) music into small computer files. You may download MP3 music several ways: Music can be downloaded from websites that have turned wide music libraries into MP3. Once MP3 music is on your PC’s hard drive, you can play it through your computer's speakers, burn it onto blank CDs or swap(交换) MP3 files with friends using e -mail. How much? Software needed to play and turn MP3 music is often free. Compact要除去盛有空气的密闭容器里的氧气得到较纯净的氮气，可用燃烧除去氧气的方法，下列物质可选用的是(      )A、红磷    B、蜡烛    C、木炭    D、铁丝