1. To remove the word "yes", you can extract the trunk. If you want to use the word "yes", it must be preceded by a subject, and the previous sentence is a complete sentence guided by "because", so you can't add the word "yes".

2. Replace "at present" with "a few days ago"

3. Before "because" is removed, a term is needed because "is the main factor that causes the sharp decline of natural lakes and their wetlands".

4. Lock the target. . . After exceeding the standard, add "the problem"

5. Switch between "destruction" and "injury"

6. Add the word "has" after "its name"