导致牙髓病和根尖周病的主要因素是()
A.物理刺激
B.化学刺激
C.细菌感染
D.外伤
E.免疫反应
参考答案:C
定员管理
----- Would you mind helping me with my suitcase? I really can’t manage it by myself.
----- ________.
A.My pleasure
B.No problem
C.Not at all
D.Never mind