It is only gradually, with the passing of years, _____ to a clear understanding of their position.

A．that they come

B．do they come

C．that come

D．when they come

目前，计算机病毒传播最快的途径是( )。

A．通过软件复制

B．通过网络传播

C．通过磁盘拷贝

D．通过软盘拷贝