All but one＿＿＿＿take part in the conference＿＿＿＿tomorrow.

A．is going to； that is to take place

B．are going to； that is about to take place

C．are going to； that is to be taken place

D．are going to； which is to be held

患者，男，37岁，因釉质发育不良而面严重磨损。检查：活髓牙，面广泛缺损，无龋坏，不松动，与对颌牙间有约1.0 mm咬合间隙，邻接正常，余无特殊，拟为该患者进行高嵌体修复

利用的主要固位方式是下述哪一项（）

A．环抱固位形

B．洞固位形

C．沟固位形

D．钉洞固位形

E．倒凹固位形