A.1/1000 B.1/800 C.1/1500 D.1/2000
A.e≤0.2δ,且e≤2.5mm B.e≥0.2δ,且e≤2.5m C.e≥0.2δ,且e≥2.5mm D.e≤0.2δ,且e≥2.5m
A.≤0.2 B.≤0.3 C.≥0.2 D.≥0.3