cycle

/ˈsaɪkəl/

an interval during which a recurring sequence of events occurs

中文释义：循环；周期

The water cycle plays a crucial role in maintaining the Earth's climate.

水循环在维持地球气候方面起着关键作用。

Economic cycles of boom and bust are inevitable in capitalism.

资本主义经济中繁荣与萧条的周期是不可避免的。