实例表明厚度为0.0672mm的结垢会使通流容积减小1%,级效率下降()。
A.3%-4%
B.0.3%-0.4%
C.3%-5%
D.4%-5%
参考答案:A
—Look at the boy running on the ground. Is it Davis?
—It ______ be him. I saw him go to the teacher’s office just now.
A.mustn’t
B.can’t
C.could
D.might
远中孤立,向近中舌侧倾斜的下颌磨牙常设计
A.圈形卡环B.回力卡环C.联合卡环D.倒钩卡环E.延伸卡环