7. His mother always used her favourite cups and the special set of spoons (KNIFE) and forks.

Solution:

The sentence lists items used for eating. 'Spoons' are followed by a blank and then 'forks'. The missing item from the set is 'knives'. The word 'KNIFE' needs to be in its plural form to match 'spoons' and 'forks'.

Answer: 7. His mother always used her favourite cups and the special set of spoons, knives and forks.