Economic crises recur periodically.是什么意思？

Economic crises recur periodically.

经济危机周期性地发生.

economic

adj. 经济的，经济学的，合算的，有经济效益的；

例句
He's already altered several of the proposals in his economic plan to accommodate demands of special interests.
他已经改动了经济计划中的几项提议以迁就特殊利益集团的要求。

crises

n. 危险，危险期，紧要关头，危机（ crisis的名词复数 ），危难时刻，决定性时刻，转折点；

例句
There would be fewer international crises demanding his attention...
需要他去关注的国际危机将会减少。

recur

vi. 再发生，复发，重现，回想；

例句
...a theme that was to recur frequently in his work.
一个在他的作品中反复出现的主题

periodically

adv. 周期性地，定期地，偶尔；

例句
Henke said. " Yoko would periodically call and speak to whoever answers. "
洋 子会定期打进来,跟接电话的人讲话,不管谁接.