（）提高体育教学训练质量的必要途径。
参考答案：体育科研
They told us that these small apples are often sweeter than big ____.
A．those
B．one
C．that
D．ones
慢性龋又称为（）
A.浅龋
B.潜行性龋
C.静止龋
D.干性龋
E.继发性龋
