光滑水平面上的物体，在水平方向只受一对平衡力的作用，则该物体（　　）

A．可能在水平面上向任意方向做匀速直线运动

B．只能以一定的速度做匀速直线运动

C．只能沿一个力的方向做匀速直线运动

D．不是静止就是沿力的方向做匀速直线运动

NAC’s (Network Access Control) role is to restrict network access to only compliant endpoints and (81) users. However, NAC is not a complete LAN (82) solution; additional proactive and (83) security measures must be implemented. Nevis is the first and only comprehensive LAN security solution that combines deep security processing of every packet at 100Gbps, ensuring a high level of security plus application availability and performance. Nevis integrates NAC as the first line of LAN security (84) In addition to NAC, enterprises need to implement role-based network access control as well as critical proactive security measures-real-time, multilevel (85) inspection and microsecond threat containment.

A．constructive

B．reductive

C．reactive

D．productive