30.製作可撤式局部義齒時,模型上那些區域不需要作平行式封凹(parallel blockouts)?
(A)需被剛性連接體跨越的組織倒凹(tissue undercuts to be crossed by rigid connectors)
(B)槓狀牙鉤之下的組織倒凹(tissue undercuts beneath bar-clasps)
(C)作為導引面的牙齒臨接面(proximal tooth surfaces to be used as guiding planes)
(D)在金屬支架遠心端之後的組織倒凹(tissue undercuts distal to cast framework)