一光线以很小的入射角i射入一厚度为d、折射率为n的平板玻璃，求出射光线与入射光线之间的距离。（θ很小时，sinθ≈θ，cosθ≈1）
However difficult you find to arrange your time, it will pay off in the long run.
A．this
B．one
C．it
D．that
股骨头坏死如何诊断？
