以下均是增强桩冠固位的方法，除了（）。

A.尽可能利用牙冠长度

B.尽可能多保留残留牙冠组织

C.根管口预备成一个小肩台

D.用铸造桩增加冠桩与根管壁的密合度

E.根管预备成喇叭口状

根据句意及所给中文提示或首字母提示，写出句中所缺单词。

小题1:We know a lot about that great ____________ (宫殿).

小题2:We all know that Beijing is the c____________ of China.

小题3:I’m going to be an ____________ (艺术家) in the future.

小题4:My home is about fifteen ____________ (英里) form my school.

小题5:John’s grandfather is old, but he still wants to learn some ____________ (技能).