Baking soda makes a great natural stain remover. It's gentle enough to use on almost any type of fabric. Mix a tablespoon of baking soda with enough water to make a thick paste. Alternatively, mix the baking soda with hydrogen peroxide or white vinegar.  Baking soda paste is best used on fabrics that don't require dry cleaning. You'll have to rinse it away when you're finished, so the clothes will get wet. Baking soda paste works well to remove stains caused by oil, grease, dirt, food, and many other substances. Lightly rub it into the stain. Make sure it covers the entire stained area, overlapping the edges. Allow it to sit on the stain for 15 minutes.  If the stain is on sturdy clothing, you can scrub it using an old toothbrush. Scrub the baking soda into the stain to make sure it can treat all of the fibers. This method is fine to use on denim and thick cotton. Don't scrub the baking soda into delicate fabric. Silk, satin and other thin fabrics could warp when scrubbed. Run it under warm running water to rinse away the baking soda along with the stain. For more delicate fabrics, you can wipe away the baking soda using a dampened cloth. Some difficult stains require more than one treatment. Apply a second round of paste to the stain. Let it sit for 15 minutes, then rinse it away. If the stain remains, you may need to use a chemical stain remover or take the item to be professionally cleaned.

TL;DR in Chinese:
制作小苏打糊。 将小苏打糊涂在污渍上。 洗掉小苏打糊。 必要时，可以重复上述过程。