保持铁口深度的关键是（）。
A.长铁口
B.出净渣铁
参考答案：B
上牙槽后神经阻滞麻醉是将药物注射于__________后外方，麻醉上牙槽后神经。
we were ______ at the news of her sudden death.
A．astonishing
B．to astonish
C．astonished
D．astonish
