Answer:
Take one royal word in the plural and make it singular by adding one letter
Bobby likes Jimmy but not Joe, apples but not pears, jeeps but not vans, shinny but not hockey, tennis but not squash. Who will he like, Sara or Sally?
These are needed to finish a test
What can you hold in your left hand but not in your right hand?
A king wears one on his head.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?