pool of available nodes

例句：

1. 1. The children gathered around the pool to play.
   孩子们围在游泳池周围玩耍。
2. 2. The fish swam in the pool and looked happy.
   鱼在池塘里游来游去，看起来很高兴。
3. 3. The pool was filled with water from a nearby river.
   池塘里充满了附近河流的水。