1. Have Harry and Sue ever explored a cave?

2. My car has never broken down before and I don't know what to do. What a nightmare!

3. John hasn't visited China before.

4. I have been sailing once, but I didn't like it. The sea was rough and I got seasick.

5. Have you tried waterskiing before? — No, but I'd love to.

— I have been waterskiing once and it's amazing. Let's go together next time. — Sure.

6. The girls haven't seen this film before.