A Bluetooth device can be either a master or a slave and any of the devices within a （  ）can be the master. There is only one master and there can be up to （  ）active slave devices at a time within a single network. In addition， a device may be a standby slave or a parked slave. There can be up to （  ） parked slaves. If there are already maximum number of active slaves， then a parked slave must wait until one of the active slaves switches to （  ）mode before it can become active. Within a network， all （  ）communications are prohibited.