小儿几岁时听觉发育完善（）
A.1岁
B.2岁
C.3岁
D.4岁
E.5岁
参考答案：D
标准直齿圆柱齿轮的全齿高h=9mm，其模数为（）。
A.3mm
B.4mm
C.2.5mm
D.2.25mm
— It was ______ of Jack to turn off the radio when I was sleeping in the bedroom.
— So he was. [ ]
A. reasonable
B. sensible
C. considerate
D. generous
