Question tags, typed rather than chosen: “Let’s go trick-or-treating, …?”, “This is a great party, …?”, “Everybody’s dancing, …?”. Each sentence needs its own tag – shall we, isn’t it, aren’t they.
Tags are where learners who are otherwise fluent still stop to think: the auxiliary, the pronoun and the polarity all have to match the main clause, and let’s and everybody break the usual pattern.