A.10~2000Hz B.10~1500Hz C.100~2000Hz D.100~1500Hz
A.>10 B.≥10 C.≥5 D.>5
A.設(shè)計強度的70%,且不小于15MPa B.設(shè)計強度的30%,且不小于12MPa C.設(shè)計強度的70%,且不小于12MPa D.設(shè)計強度的30%,且不小于15MPa