Reading - context, detail and vocabulary

Article: PhD student finds lost city in Mexico jungle by accident
Source: BBC

The .pdf includes line numbers, referenced using format 2-12 = page - line.
You can download the article (.pdf) or read it through this link.
Questions
[format 2-12 = page - line number]
  1. In 2-1, why is the present perfect tense used?
  2. What does peak (2-43) refer to?
  3. How does mostly affect the sentence in 2-71?
  4. According to the paragraph, from 3-9 to 3-12, there is hidden treasure: true or not?
  5. Why introduce the sentence with 'the point is' 3-31?
  6. Why does the article use suggest in 3-36?
  7. Why does the sentence use the present perfect and not past simple or past perfect in 3-54?
  8. Write a sentence using downside 4-1, in relation to your work.
C o u r s e s    -   C o a c h i n g   -   T e x t s m i t h  -  L i b r a r y
W o r k s h o p s   -  O u r  w o r k    -   A b o u t  
  C o n t a c t  -   P r i v a c y   -   T e r m s   &   C o n d i t i o n s
E N G L I S H,  S I M P L Y
C O P Y R I G H T  2 0 2 3