Please come back soon.

请马上回来。

I shall come back soon and show you what I have brought home with me.

我马上就回来，给你们看看我带回来的东西。

Stay here. I will come back soon.

呆在这儿。我很快会回来。

Butt I will come back soon.

但是我很快就会回来。

But I will come back soon.

但是我很快就会回来。