We need to evaluate the cost-effectiveness of this project.

A diagonal matrix is a matrix in which all elements outside the main diagonal are zero.

The diagonal elements of this matrix are all 1.

We should always remember the power of Kannon in difficult times.

Makoto is my best friend.

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.