feel free to  随心所欲地做某事

　　Please feel free to have another. 别客气，再来一个。

　　Feel free to stay here as long as you like. 想待多久就待多久。

　　Feel free to ask if you have any questions. 如果有问题的话，可以随便问。

　　Feel free to stay here as long as you like.  只要你喜欢，想待到什么时候就待到什么时候。

　　It's very kind of you to say so.  你能那么说，我很高兴。