61. our rivers/ streams/ seas/ dirtied/ activities on land
=> Our rivers, streams, and seas are being dirtied by activities on land.
62.forest / important economic value/ because /they provide / us/ resources such as timber
=> Forests have an important economic value because they provide us with resources such as timber.
63. forest / vital / the environment / because /they/ clean/ air / we breathe
=> Forests are vital to the environment because they clean the air we breathe.
64. man/ cut / too many trees/ over the years / and/ we now face up/ problem / deforestation 
=> Man has been cutting too many trees over the years and we now face up with the problem of deforestation.
65.the forest / still a place / hold/ many / world's most valuable resources 
=> The forest is still a place that holds many of the world's most valuable resources.