Non-defining relatives clauses

The Javan tiger, --------habitat was largely destroyed by humans, is now extinct.

The hostel, ______we've stayed at several times, is simple but clean.

They went to a concert at the new arena, ____was built last year.

When I left they threw me a party, ______was a complete surprise.

My birthday, ____was my 40th, turned out to be a wonderful day!

I sometimes go and study in my local park, ______I can get some fresh air.