You should turn off devices that you are not using to ______ electricity.

• save

• reuse

• release

• turn

"Carbon footprint" is the amount of carbon dioxide that we ______ into the environment.

• stop

• plant

• recycle

• release

We should ______ our carbon footprint to protect the environment.

• pollute

• protect

• reduce

• endanger

Forests help release oxygen and absorb __________________

• carbon dioxide

• global warming

• environmental protection

• water pollution

We can take part in activities like picking ______ and planting trees to protect nature and the environment.

• up

• about

• down

• to

He won't get paid for time off ______ he hasn't got a doctor's note.

• unless

• till

• because

• if

The gases from the exhausts of cars have also increased ______ pollution in most cities.

• land

• sand

• water

• air

I don't know the reason ______ you didn't go to school.

• what

• whose

• why

• where

A number of cleaning products contain ______ chemicals

• safeful

• helpful

• harmful

• hopeful

They can ______ campfires on the beach near the hotel.

• volunteer

• cut

• build

• litter