我想给他们一些东西，以回报他们为我们所做的一切。

I'd like to give them something ___in ___return for everything they've done for us.

我过得很愉快，作为回报，我想邀请你在我家住宿，当你在波兰时。

I had a great time and ___in ___return I'd love to invite you to stay at my house while you are in Poland.

她帮助了我的项目，作为回报，我提出帮助她的项目。

She helped me with my project, and ___in ___return I offered to assist her with hers.