Please explain the meaning of these couplets.

What you get on paper is so shallow that you never know what you have to do.

Ask where the canal is so clear, because there is running water at the source.

The world is full of knowledge and the cultivation of human feelings is an article.

Although it is hard, it is difficult to blow out crazy sand when it is not golden.

I quit my job and go home, just like a flower falling from a branch, but this is not a heartless thing. It can be turned into the soil of spring and can also play a role in nurturing the next generation.

Only "everything is learned, and people's understanding is an article." You can do couplets, and the rest are the end of a poem (quatrains), but you can't do couplets.

The ancients learned nothing, and it takes time to grow old. What you get on paper is so shallow that you never know what you have to do. The last two sentences mean that what you get from books is always superficial. If you really understand these things, you have to do it yourself.

Half an acre of square pond was opened all the way, and the mountains were shrouded in clouds. I wonder why the canal is so clear, because there is running water at the source. The last two sentences mean: Why is this half-acre square pond so clear? Because the flowing water from the source keeps flowing in.

The world is full of knowledge and the cultivation of human feelings is an article. This is a true couplet from A Dream of Red Mansions. It means: knowing the world is learning, and having a set of coping skills is also an article.

Mo Tao's slanderers are as deep as waves, and Mo Yan's guests are as heavy as sand. Although it is hard, it is difficult to blow out crazy sand when it is not golden. (Liu Yuxi's "Langtaosha") The last two sentences mean: Although you have worked hard for thousands of times, blowing up the sand is gold.

The vast sadness of parting extends to the setting sun, away from Beijing, riding a whip to the east, feeling that people are on earth. I quit my job and go home, just like a flower falling from a branch, but this is not a heartless thing. It can be turned into the soil of spring and can also play a role in nurturing the next generation. (Gong Zizhen's Ji Hai Miscellaneous Poems) The last two sentences mean that the fallen flowers on the tree are not things without feelings, they will turn into spring mud to protect the flowers in the coming year.