I'd like to stay _______ my mother, I miss her. [ ]
A. with
B. at
C. by
D. from
答案:A
简述固定修复体的固位原理及临床应用:粘结力。
在国外,国库券利率往往被称为无风险利率,这表明国库券投资不存在任何风险。( )