关于显像时间的叙述，错误的是

A．肾动态显像每30～60s采集10帧
B．肝胆动态显像每5～15min采集1帧
C．心脏首次通过显像每50ms左右采集1帧
D．显像剂在体内运转较慢时，采集的速度要慢
E．显像剂在体内运转速度快，采集的时间间隔应短

A Bluetooth device can be either a master or a slave and any of the devices within a ___30___can be the master. There is only one master and there can be up to ___31___ 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 ___32___.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 ___33___ mode before it can become active. Within a network, all ___34___ communications are prohibited.

31（）

A.7 

B.15 

C.63 

D.255