nag (away) at someone
phrasal verb with nag verb [ I or T ] uk/næɡ/ us/næɡ/ -gg-
（疑虑或担心）不断困扰，不断烦扰（某人）
If doubts or worries nag (away) at you, you think about them all the time.
The same thought has been nagging away at me since last week. 自从上周开始，同样的想法就一直困扰着我。