People are destroying the environment by adding ____ to it.

Many efforts have been made to protect ____ nature.

Many species of animals are threatened and could easily become ____.

. Many animals are ____ for their fur and other valuable parts of their bodies.

Oil, coal and natural gas are ……………..

____ heat comes from deep inside the earth.

Biogas is the largest energy ……………..available in rural areas in developing countries.

Solar energy is not only plentiful …………….clean and safe.

The volunteers help the victims...................houses were destroyed in the floods