He studied English for ____ in London, and then he went to America. [ ]

A. sometimes

B. sometime new

C. some time

D. some times

女性，36岁。右上中切牙牙冠3／4缺损，叩痛（-），不松动，牙龈无红肿，X线片示根管治疗完善，根尖无阴影。最适合的修复治疗方案是（）

A.嵌体

B.3／4冠

C.开面冠

D.桩核冠

E.全冠