Questions

India   signed   a   historic   deal   to develop    the    strategic    port    of Chabahar  in  Iran  and  agreed  on  a three-nation    pact    to    build    a transport-and-trade corridor through   Afghanistan   that   could help  halve  the  time  and  cost  of doing  business  with  Central  Asia and     Europe.     Developing     the  Chabahar  port  was  seen  as  crucial for  India  because  it  will  not  only allow New Delhi to bypass Pakistan and access global markets but also counter    China’s    expanding influence   in   the   Indian   Ocean region. But the project’s land route through   Afghanistan   remains   a security headache

Rainforests are very dense, warm and wet forests. The reason it is called a "rain" forest is because of the high amount of rainfall it gets per year.

The error is in second part. In the given sentence two events occur one after the other. ‘He left’ before ‘we reached’. So, the event that was completed before the occurrence of the next event shall be expressed in past perfect tense. Therefore, the correct form of verb will be “had left”.