A Bluetooth device can be either a master or a slave and any of the devices within a （71） can be the master．There is only one master and there can be up to （72） 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 （73） 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 （74） mode before it can become active．Within a network, all （75） communications are prohibited.

空白处（72）应选择（）

A．7

B．15

C．63

D．255

下列反应中，既属于化合反应，又属于氧化反应的是

A．水氢气＋氧气　　　

B．氧化钙 + 水氢氧化钙

C．乙炔＋氧气水＋二氧化碳

D．磷＋氧气五氧化二磷