A

• Now Robert is at work.
  
• At midnight last night he wasn’t at work.
  
• He was in bed.
  
• He was asleep.
  

• I am tired. (now) → I was tired last night.
  
• Where is Kate? (now) → Where was Kate yesterday?
  
• The weather is good today. → The weather was good last week.
  

You are late. (now) → You were late yesterday.
They aren’t here. (now) → They weren’t here last Sunday.

B

• Last year Rachel was 22, so she is 23 now.
  
• When I was a child, I was afraid of dogs.
  
• We were hungry after the journey, but we weren’t tired.
  
• The hotel was comfortable, but it wasn’t expensive.
  
• Was the weather nice when you were on holiday?
  
• Your shoes are nice. Were they expensive?
  
• Why were you late this morning?
  

C

• “Were you late?” “No, I wasn’t.”
  
• “Was Ted at work yesterday?” “Yes, he was.”
  
• “Were Sue and Steve at the party?” “No, they weren’t.”