That issue is irrelevant to our discussion.

His opinion is irrelevant to this issue.

They built a deep emotional bond before they had a physical relationship.

He is an expert in international relations.

In Marxism, it is said that the relations of production form the foundation of society.

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.

Believing that failure is a stepping stone to success, he challenged again.

Believing that failure leads to success, he continued to challenge himself over and over again.