How to take part of the formula from another cell?

Question

Spreadsheets

Tell me how to take part of the formula from another cell, for example:
Full formula:
=IMPORTRANGE("link";"June2020!o2:o2")
the second part is "June2020!o2:o2", I want to take from the cell, you can use the entire text , you can, for example, insert only months in parts, for example, July, and so that the formula works.
I want to pull up the values ​​from different tabs for different months, but at the same time not to edit the formula manually every time.