The houses          . They will be finished next year.

A．are built

B．have been built

C．are being built

D．were built

OSI架构中的（）将网络数据传输的内容解释为对用户有意义的形式，包括对于数据所使用编码的转换。

A.理层

B.话层

C.示层

D.用层