After hard work and bumps in the world of mortals, we have met many people of all kinds who have come and gone around us. Some people are just passers-by in our lives, coming and going without a trace; some people are destined to stay together for a lifetime, but they cannot stir up a single wave in their hearts and are indifferent; some people just glance at them, but they take root in their hearts and even miss them for a lifetime.