something you say when you pause while talking or when you are uncertain

"Which one do you like best?" "Hmm. I'm not sure." “你最喜欢哪个？”“呃，我也拿不准。”

"He says he's doing it for our benefit." "Hmm, I'm still not convinced." “他说他那么做是为了我们好。”“嗯，我仍然不太相信。”