单项选择题
A.≥50% B.≥43% C.≥36% D.≥29%
A.≥0.2Mpa B.≥0.30Mpa C.≥0.40Mpa D.≥0.50Mpa
A.≥4.5mm B.≥5.0mm C.≥5.5mm D.≥6.0mm