it is/was nothing

used to tell someone not to worry about, or place special value on, what you are doing or have done

别担心;没什么要紧的

"You seem very upset."

"No, no, it's nothing - I'm OK."

“你看上去很不安。”

“不，不，没什么，我很好。”

"It was so nice of you to look after the baby all day."

"Oh, it was nothing, I enjoyed it."

“谢谢你一整天照顾宝宝。”

“哦，没什么，愿意效劳。”