拔牙时牙槽骨折断的常见原因有()
A.去除骨质太多
B.使用牙挺时用力过急过猛
C.用力不当
D.牙根与牙槽骨粘连
E.牙根形态异常粗壮
参考答案:A, B, C, D, E
13._________his size, I guessed that he was a basketball player.
A.To judge from
B.Having judged by
C.Judging from
D.Judged by
下列关于化学反应“2XY2+Y2=2Z”的叙述错误的是( )
A.Z的化学式为XY3
B.若mgXY2和ngY2充分反应后,则生成Z的质量不大于(m+n)g
C.若XY2和Y2的相对分子质量分别为M和N,则Z的相对分子质量为(M+N)
D.若agXY2完全反应生成bgZ,则同时消耗(b-a)gY2