骨上袋的特点,除外()
A.常指单面袋
B.牙槽骨一般呈水平吸收
C.牙槽骨不构成牙周袋壁
D.袋底位于釉牙骨质界的根方
E.袋底位于牙槽嵴的冠方
参考答案:A
He is a key _____ in the murder so we must protect him from all kinds of danger.[ ]
A. witch
B. watcher
C. wizard
D. witness
“划小船”