多媒体PC配置方案中，可以不配置的是（）。
A.声音卡
B.视频卡
C.扬声器
D.CD-ROM驱动器
参考答案：C
If you had helped him, he _________happy now. [ ]
A.is
B. would have been
C. Was
D. would be
Access数据库的核心是______。
