5. By 5 o'clock the day before yesterday Carol (to play) badminton with Denis in the garden and at 6 o'clock they (to sit) and (to eat) tasty ice cream in the sitting room.

Solution:

• 5. By 5 o'clock the day before yesterday Carol had played badminton with Denis in the garden and at 6 o'clock they were sitting and were eating tasty ice cream in the sitting room.

Explanation: Playing badminton was completed by 5 o'clock (Past Perfect). Sitting and eating were ongoing actions at 6 o'clock (Past Progressive).