He was out of breath after running a long distance.

He explained the importance of studying while young, saying 'If you do not study when you are young, it will be difficult to learn when you are old.'

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.

I fed the pigeons in the park.

I would rather go alone.