The answer to the first one is A because only A describes something that is happening right now, and only A clearly involves the speaker making the invitation to the listeners.. Sentence B could be used the same way, but is often used to talk about a PLAN to make invitations. Example: “Dad, I’m inviting Susan to have dinner with me. I am going to call her later tonight and extend the invitation.” The answer to the second one is B because only B describes an ongoing situation — the dance group is appearing at the theatre (for a number of nights). Sentence A, in contrast, talks about a single point in time.