A、Adding chicken waste in them. B、Combining them with traditional plastic. C、Putting household waste in them. D、Selling them onl

　　Chicken feathers are useful, and not just to a chicken. Some go into pillows, coats and other products. But countless chicken feathers go to waste. In the United States, billions of chickens are produced yearly. Most of their feathers are thrown away. But instead of being buried in the land, some feathers could find a future in plastics. One of the products made from the feathers is a flowerpot. It may look like other flowerpots. (16)But it is really good for the environment. That’s because it is much easier for feather flowerpots to break down in the earth within 1 to 5 years. And as it breaks down, it naturally adds some nutrients to the soil. The flowerpots are made by reducing chicken feathers to a powder. Then the powder is shaped into pots. The environmentally friendly flowerpot is the work of two researchers. Walter Schmidt is with the Agricultural Research Service, part of the United States Agriculture Department. Masud Huda is with the Horticultural Research Institute, a private organization. Walter Schmidt has been working to find uses for chicken feathers since the 1990s. (17) Progress in 2002 showed that plastic made from feathers could be formed like other plastics. He says plastics made by feathers are much stronger. (18) But traditional flowerpots can last much longer. He wonders if there is really a need. He says most flowerpots are never reused. (19) Walter Schmidt and Masud Huda are now trying to add another chicken product to their flowerpots—chicken waste. The waste will add more nutrients to the soil as the pot breaks down. The scientists say they hope their flowerpot will be on the market in one year or two.
　　16. Why does the speaker say the feather flowerpot is environmentally friendly?
　　17. What’s the difference between traditional plastic and plastic made from feathers?
　　18. What is Walter Schmidt’s opinion about traditional flowerpots?
　　19. How will the two researchers improve their flowerpots?