Missing is like a ball of thread that cannot be pulled. If it accidentally rolls to the ground, you can only run to chase it. When you bend down and stop breathing hard, you will only have a bunch of messy threads in your hand. You can't find the beginning or the end. But you still can't bear to throw it away. After sorting it for a long time, it turns into a ball of thread. You carefully bury the thread and hide it in your backpack. But at the next moment, you can't help but take it out and hold it in your hand, not daring to let go for a moment.