The fidelity of this television is very high.

He is good at writing, especially at writing poems.

He is a good correspondent, always writing letters.

He is a very diligent person.

His diligence in his work was appreciated, and he was promoted.

His disloyal actions deeply hurt his friends.

This ancient proverb, 'know the other side and yourself, and you will not be in danger in a hundred battles', teaches us the importance of understanding ourselves and others.