自由自在用英语可以说成 "at ease" 或者 "free and easy." 这个词组最早可能来自于古英语，其中 "at ease" 的意思是指放松，舒适，没有压力或担忧。"Free and easy" 则指轻松，自然，没有限制或拘束。

一些例句如下：

After a long day at work, I like to relax at home and feel at ease.

The weather was so nice that we decided to take a walk and enjoy the free and easy atmosphere.

The speaker was so funny and engaging that the audience was soon at ease and laughing along.

We enjoyed a leisurely breakfast and then spent the day exploring the city in a free and easy way.

以上例句的中文翻译如下：

工作了一整天后，我喜欢在家里放松，感觉轻松自在。

天气非常好，我们决定散步，享受自由自在的氛围。

演讲者很风趣，很容易打动听众，很快大家都感到轻松愉快。

我们悠闲地享用早餐，然后整天都在城市中随心所欲地游玩。