悬空式桥体龈面至牙槽嵴黏膜的距离至少为（）
A.0.5mm
B.1.0mm
C.1.5mm
D.2.0mm
E.3.0mm
参考答案：E
Some people try to knock me down, only______ me more determined to do better. [ ]
A. to make
B. makes
C. having made
D. made
下列哪一项是属于物理因素所引致危害?
A.铅尘
B.木屑
C.热衰竭
