如何合并两个有说服力的集合?

I have a questions table, and a tags table. I want to fetch all questions from tags of a given questions. So, for example, I may have the tags "Travel", "Trains" and "Culture" attached to a given question. I want to be able to fetch all questions for those three tags. The tricky, so it seems, is that questions and tags relationship is a many-to-many defined in Eloquent as belongsToMany.I have a questions table, and a tags table. I w