After graduating from the military academy, he joined the army.

Please find the square root of this number.

This room is 20 square meters.

The size of this room is about 20 square centimeters.

This city has an area of about 20 square kilometers.

This is our common life.

I maintain my health by doing aerobic exercises every day.

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

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.