There was a demonstration where you live, wasn't there?
People held a demonstration in your town, didn't they?
この場合、次のような言い方ができますよ。
ーThere was a demonstration where you live, wasn't there?
「あなたの住むところでデモがあったんだよね？」
ーPeople held a demonstration in your town, didn't they?
「あなたの街でデモがあったんだって？」
ーAre there a lot of demonstrations there?
「そこではよくデモがあるの？」
デモは demonstration の他に protest とも言えます。
ご参考まで！
カナダ 
