RFID卡()可分为:有源(Active)标签和无源(Passive)标签。
A、按供电方式分
B、按工作频率分
C、按通信方式分
D、按标签芯片分
参考答案:A
Jess was sad and her friends helped her ________ the first awful weeks after her husband Bill died.[ ]
A.break through
B.break down
C.get through
D.get rid of
配对计数资料χ2检验公式,其分子是()
A.|b-c|
B.|b-c|-1
C.|b-c|-1)2
D.b+c