— Do you think the article is difficult?    

— I think so. It took me a long time to _____ the new words in the dictionary. [ ]

A. look at

B. look out

C. look for

D. look up

患者男，因上前牙牙龈反复出现瘘管，X线片显示根管钙化，经过多次正规治疗后无效，拟行根尖手术，手术切口设计中错误的是（）。

A.牙周组织的健康程度影响愈合

B.切口下方必须有骨组织支持

C.瓣膜蒂可小于游离端

D.切口不应通过骨隆突

E.切口边缘不能被撕裂