closed system的用法和樣例：
例句
- People were not necessary for a closed ecosystem to run once stable, but they might be helpful in stabilizing it.
封閉系統一旦進入穩定運行，人類就不是必不可少的部分，不過，他們可能會有助於其穩定。 - Dowling points out that excess ink is recirculated within the sealed system, reducing consumption and contamination from lint, dust or dampener fluid.
道林指出，過剩的墨水循環的封閉系統，減少消耗和污染皮棉，塵埃或沮喪液。
