A.5cm B.10cm C.15cm D.20cm
A.10mm B.1mm C.0.1mm D.0.01mm
A.權(quán)倒數(shù)較大 B.權(quán)倒數(shù)較小 C.任一權(quán)倒數(shù) D.權(quán)倒數(shù)平均值