1) General question: Who is walking in the park now?
Alternative question: Are they walking in the park now or in the store?
Special question: Where are they walking now?
Tag question: They are walking in the park now, aren't they?
Subject question: Who is walking in the park now?
2) General question: What did she buy last year?
Alternative question: Did she buy a new car or a new house last year?
Special question: When did she buy a new car?
Tag question: She bought a new car last year, didn't she?
Subject question: What did she buy last year?
3) General question: What have they bought?
Alternative question: Have they bought a new car or a new house?
Special question: What have they bought recently?
Tag question: They have bought a new car, haven't they?
Subject question: What have they bought?