氢气浓度的稳定会提高预聚物质量，使细粒含量（）
A.增加
B.降低
C.不确定
D.无影响
参考答案：B
The loss has not yet been ____ accurately, but it is believed to be well beyond a hundred million dollars. [ ]
A. calculated
B. considered
C. completed
D. controlled
只能在方形弓丝上完成的第三序列弯曲为
A．倾斜移动B．转矩C．差动力原理D．缺隙保持器E．序列拔牙法
