她的偏头痛每个月都会复发。

Her migraines ___recur every month.

那首老歌的旋律总是不经意间浮现在我的脑海。

The melody of that old song keeps ___recurring in my mind.

这个数列中的数字每三个项就会重现一次。

The numbers in this sequence ___recur every three terms.