1) fossil fuel include the following except a) coal b) petroleum c) helium gas d) natural gas 2) humans burn fossil fuels to  a) move vehicles b) cut trees c) generate electricity d) move vehicles and generate electricity 3) taking in oxygen and removing CO2 is  a) burning fossil fuels  b) photosynthesis c) respiration 4) co2 levels can -----------increase by volcanic eruptions  a) naturally b) indirectly c) unnaturally 5) when dead animals and plants are broken down a) respiration b) decomposition c) photosynthesis d) burning fossil fuel

human activities

만든이
인쇄
퍼가기

순위표

비주얼 스타일

옵션

템플릿 전환하기

자동 저장된 게임을 복구할까요?