A.0.1~0.2B.0.2~0.3C.0.5~0.6D.0.3~0.4
A.小于90°B.等于90°C.大于90°D.小于100°
A.盡量緊點(diǎn)B.盡量松點(diǎn)C.松緊適當(dāng)D.松緊度隨意