[单选] 因列车满员、晚点、停运等原因，使旅客在规定的（）内不能到达到站时，车站可视实际需要延长通票的有效期。

Which two of these statements regarding RSTP are correct?（） RSTP cannot operate with PVST+.。 RSTP defines new port roles.。 RSTP defines no new port states.。 RSTP is a proprietary implementation of IEEE 802.1D STP.。 RSTP is compatible with the original IEEE 802.1D STP.。 What are two enhancements that OSPFv3 supports over OSPFv2? （） It requires the use of ARP.。 It can support multiple IPv6 subnets on a single link.。 It supports up to 2 instances of OSPFv3 over a common link.。 It routes over links rather than over networks.。 载体 what is the attributes that are required to be sent to BGP neighbors？ 麦芽皮壳分离、分级糖化法。 因列车满员、晚点、停运等原因，使旅客在规定的（）内不能到达到站时，车站可视实际需要延长通票的有效期。