2. Answer: This sentence uses column number and comparative explanation method, which better explains the characteristics that the waste of this product is easy to degrade or the degradation speed is very fast.
3. Answer: No, because the limitation of the "main" list means that most of the carbon dioxide comes from these factories, but other channels are not excluded. If it is deleted, it is inconsistent with reality and reflects the accuracy of the interpretation language.
Hehe, I just wrote it