annular cluster of engines

例句：

1. 1.The moon is an annular object in the sky.
   月亮是一个天空中的环状天体。
2. 2. The planets are often described as being annular.
   行星通常被描述为环形的。
3. 3. The sun is an annular star.
   太阳是一个环形恒星。