We use "突然ですが”, when we change the subject. situation: I know it is sudden, but.... Some quizmaster use "突然ですが” as the first word, when he gives a quiz. situation:"It's quiz time. What do you think ...". 他にも使い方があるので、わからなければ質問してください！

It is used when you want to say something like: I'm sorry for such short notice, but... 突然ですが、来週ジュネーブに行くことになりました。 I'm sorry for such short notice, but I am coming to Geneva next week.

i don't think it should be "が” there .. shouldn't it be "か” ? "Totsuzen" means sudden. 突然ですが- It's sudden but... 突然ですか- Isn't it sudden?