elliptical time base

例句：

1. 1. Theshape of the planet is elliptical.
   这个星球的形状是椭圆的。
2. 2. The elliptical orbit of the moon around theearth is well-known.
   月球围绕地球的椭圆形轨道是众所周知的。
3. 3. The elliptical path of the sun across thesky is fascinating.
   太阳穿越天空的椭圆形路径令人着迷。