1. Chris and Natalie were in Athens on Wednesday. Chris wasn't in Lisbon on Tuesday. Natalie was in Dublin on Saturday. Chris and Natalie weren't in Dublin on Friday. Natalie wasn't in Budapest on Monday.
2. Was Natalie in Budapest on Wednesday? - No, she wasn't. Was Chris in Istanbul on Friday? - Yes, he was. Where were Natalie and Chris on Wednesday? - They were in Athens. Were Chris and Natalie in Athens on Thursday? - No, they weren't. Were Chris and Natalie in Dublin on Saturday? - Yes, they were.
3. Could Liam swim when he was six? - No, he couldn't. Could Martha ride a bike when she was seven? - Yes, she could. Could Martha and Liam swim when they were seven? - Yes, they could. Could Martha and Liam ride a bike when they were four? - No, they couldn't.
4. Were; couldn't; wasn't; was; were; weren't; were; was; was; were; couldn't; wasn't.
5. I was at home having dinner at seven o'clock yesterday evening. I was at my friend's at ten o'clock Saturday morning. I was walking in the park at three o'clock yesterday afternoon.