from time to time   (TTS發音)

at times；（every） now and then ；occasionally；once in a while有時；時時；偶爾；間或

    I see him at the library from time to time. 我有時在圖書館見到他。

    He called at our home from time to time. 他有時到我們家玩。

    From time to time we invite experts to give lectures in our department . 我們經常請專家來我們系講課。