不正确的避震姿势是（）。
A、趴在地上，使身体的重心降到最低
B、尽量让身体直立
C、将脸部朝下，并保持口鼻正常顺畅地呼吸
参考答案：B
We should all remember that some great scientific discoveries _____ by chance. [ ]
A. gained
B. discovered
C. occurred
D. earned
现在上颌窦根治术的编码应查找（）.
A.上颌窦根治术
B.鼻外上颌窦切开术
C.鼻内上颌窦切开术
D.上颌窦切开术
E.下鼻道开窗术
