Answer:
The author's key concept is that deforestation should be stopped. She/he expresses this by giving examples of deforestation, such as fire and trees being taken as fuel. She/he also states how 31% of the Earth is covered in forests, but this percentage is still rapidly decreasing. (there's your first three sentences. Hope this helps ^^)
Answer: Adverbial clause
Explanation: there is a main clause that has drawn so much attention. That is the average age of living independently. As is the word joining 2 separate phrases.
The speech had a massive significance in Chinese history. The people of China needed to be motivated towards the revolution the revolts wanted to bring. Thus, this speech greatly did the job. He encourages then life not lived for others is a life waste. And he emphasized his words by quoting ancient historian that dying is inevitable the only thing that matters is for what you die. His speech not only served the Chinese but also brought forward other oppressed nations to fight for their rights, top fight for the people.