A.<30° B.30°~45° C.≥45° D.>60°
A.升臂升鉤 B.升臂降鉤 C.降臂升鉤 D.降臂降鉤
A.兩點(diǎn)共弧 B.三點(diǎn)共弧 C.降鉤升臂 D.降鉤轉(zhuǎn)臂