crescent shape的用法和樣例：
例句
- When the moon was crescent shaped people began to disappear.
月亮開始呈月牙形的時候人們就開始失蹤。 - With the knowledge of Hindu trigonometric functions, two reconstructive methods, crescent and zone figure, were given by Bhaskara to prove the area formula of the sphere.
摘要婆什伽羅利用他所熟知的印度三角函數知識，給出了球表面積公式的兩種證明方法，即月牙形方法和環帶形方法。
