Q:

Gopan said to me, "Can you do these sums for me?" 

• 1
  Gopan asked me if I can do those sums for him.
• 2
  Gopan asked me if I can do these sums for him.
• 3
  Gopan asked if I could do these sums for him.
• 4
  Gopan asked me if I could do those sums for him.