—It’s a pity that Wang Qiang failed in the driving test again.

—How can you expect him to pass _______ he hasn’t been practicing enough?

A．when

B．once

C．unless

D．though

多媒体硬件系统的标志性组成有

A．光盘驱动器、CPU、软盘、A/D和D/A转换

B．光盘驱动器、有A/D和D/A转换，高清晰的彩显，数据压缩与解压缩硬件支持

C．硬盘驱动器、A/D转换、高清晰彩显、数据压缩的硬件支持

D．软盘驱动器、D/A转换、高清晰的彩显、数据压缩与解压缩硬件支持