What do you compare the teacher to? Then there are poems such as Red Candle and Spring Silkworm until the threads are dead and the wax is gone.

Compare it to a red candle that burns itself to illuminate others, or to a spring silkworm that strives to spit out the best silk. The spring silkworm's silk will not be used up until it dies, and the wax torch will not dry until it turns to ashes.

This is from

Untitled (Li Shangyin)

It is also difficult to say goodbye when we meet, the east wind is powerless and the flowers are withered.

The spring silkworms have arrived The dead thread will be exhausted, the wax torch will turn to ashes and the tears will begin to dry.

In the morning mirror, the clouds will change, and when you sing at night, you will feel the moonlight is cold.

There is not much way to go to Pengshan, the blue bird Diligently visit.