This theme recurs several times throughout the book.

这一主题在整部书里出现了好几次。

An episode of major depression may occur only once in a person's lifetime, but more often, it recurs throughout a person's life.

重度抑郁发作可能在一个人的一生中仅出现一次，但更经常的是，它在一个人的一生中反复出现。

Leap year recurs every four years.

每四年闰年一次。

A chance happens, but it never recurs.

只发生过一次，但是没再复发过。

This festival recurs every five years.

这个节庆每五年举行一次。