What is dangerous to keep at home? What is pleasant to listen to? What is important to know?

It is dangerous to keep a tiger at home. It is a wild beast and it may hurt you. Tigers are usually kept at zoos. You can keep a cat at home. It is a small version of a tiger.

It is pleasant to listen to some good songs. When you listen to some pleasant music your soul starts to sing. Doctors say good music can improve our health. 

It is important to know the grammar. It shows that you are an intelligent person. That is why you have to write in a correct way and learn grammar rules.