A.With IGMPvl， queries are sent to a specific group
B.Hosts issuing IGMPvl requests will be correctly interpreted by IGMPv2 hosts due to backwardcompatibility
C.An IGMPv2 router will ignore IGMPv2 leave messages when IGMFVl hosts are present
D.With IGMFV2， a leave message is supported
E.An IGMPv2 host will send an IGMFVl report on an IGMFVl router
F.An IGMPv2 router can only allow IGMPv2 hosts to execute a join request