She's naive. 她天真浪漫。
He's such a kid at heart. 他的心赤如童子。 Do you know how naive you sound? 你知道你的话有多天真吗？
Be careful. He's up to no good. 要注意，他存心不良。 She's not exactly a babe in the woods. 她不是省油的灯。
