Which three statements about RSTP are true?（）

• A、RSTP significantly reduces topology reconverging time after a link failure.
• B、RSTP expends the STP port roles by adding the alternate and backup roles.
• C、RSTP port atates are blocking,discarding,learing,or forwarding.
• D、RSTP also uses the STP proprsal-agreement sequence.
• E、RSTP use the same timer-baseed process as STP on point-to-point links.
• F、RSTP provides a faster transition to the forwarding state on point-to-point links than STP does.