他们面带微笑用英语怎么说

面带微笑是指脸上带有微笑的状态，可以用英语表示为 "with a smile on their face"。这是一种常用的说法，常用于描述一个人的表情或者他们正在做什么时的心情。

下面是一些例句：

The children greeted us with a smile on their faces. (孩子们面带微笑地迎接了我们。)
She answered the phone with a smile on her face. (她面带微笑地接起了电话。)
He walked into the room with a smile on his face, ready to give his presentation. (他面带微笑走进了房间，准备开始他的演讲。)