(第4空)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 maximumnumber of active slaves, then a parked slave must wait until one of the active slaves switchesto ( ) mode before it can become active. Within a network, all ( ) communications are prohibited.