We gather a great deal of incidental knowledge from pets.If we look after them properly we learn what they like and dislike. We do not set out to gain this knowledge purposely, but in attending to our pets we gain it by the way. It is got without our realizing it.     In keeping our dogs or cats we learn about various diseases that can affect them,and the cures for these diseases.We learn how much sleep they need and what kind of food keeps them healthy. In looking after our fish we learn about the composition of water.We get to know what kinds of fish can live peacefully together and what kinds are hostile to each other.We learn that animal,fish and birds have a lot of things in common with human beings. If children keep pets their general education is helped by this kind of incidental knowledge.One little incident after another in which their pets are involved adds to their store of learning.It is a more interesting form of learning than that given in the biology lesson in school.People who keep pets should have a sense of responsibility towards them.Children,too,should be taught to be responsible.Pets are completely dependent on their owners and the owners should respond to this dependence by looking after them.Irresponsible behavior towards pets is a form of cruelty.     In deciding to keep a pet we take on a task,we make ourselves responsible for providing proper food and shelter for the pet.In a crowded city like Hong Kong, where there is so little room for the exercise required by large pets,we should think  _ before undertaking the responsibility of keeping one. In keeping pets,responsibility means  _  .
depending on them taking care of them writing to them teaching them