比较两组测定结果的精密度( )。 甲组:0.19%,0.19%,0.20%,0.21%,0.21% 乙组:0.18%,0.20%,0.20%,0.21%,0.22%
A.甲、乙两组相同
B.甲组比乙组高
C.乙组比甲组高
D.无法判别