Many of Hugh's classmates (одноклассники) have got pets What must the children do?

I think Ken must feed the guinea pigs and give them water. I think he must clean the cage. I think he mustn’t often wash it.
I think Nelly must clean the cage. I think Nelly must feed the bird and give water to it. I think Nelly mustn’t walk it.
I think Pete must feed the dog and give water to him. I think Pete must walk the dog. I think Pete mustn’t ride his dog.