A.20 B.50 C.80 D.100
A.常差和不定常差 B.不定常差和標(biāo)準(zhǔn)器誤差 C.標(biāo)準(zhǔn)器誤差和復(fù)現(xiàn)性誤差 D.常差和復(fù)現(xiàn)性誤差
A.1/2 B.1/3 C.1/4 D.1/5