Conversation so far:
when was the last time man united were in the champions league
Manchester United were last in the Champions League during the 2018 - 2019 season.
When was the last time Arsenal were in the Champions League?
Arsenal were last in the Champions League during the 2016 - 2017 season.

Question: What about Milan?
Self-contained rewrite: When was the last time A.C. Milan were in the Champions League?