当采用非匀速进展横道图比较法时，如果图中同一时刻上下两个累计百分比相等，则表示( )。

A．此时刻实际进度拖后

B．此时刻实际进度超前

C．此时刻实际进度与计划进度一致

D．实际进度应采取措施加速

One feature of ______ is that it is possible to arrange for a single message to be sent to a large number of other users simultaneously.

A．Fax
B．IP telephone
C．Data Processing
D．E-mail