Understand vocabulary. Look at the following diagram. Complete the information using the words in the box. Plants help < >A、airB、controlC、dangerousD、temperatureE、water> CO2 in the air and keep Earth cool. Too much CO2 in the air is < >A、airB、controlC、dangerousD、temperatureE、water> because it causes the Earth’s < >A、airB、controlC、dangerousD、temperatureE、water> to increase. Plants take in carbon dioxide (CO2) and < >A、airB、controlC、dangerousD、temperatureE、water> (H2O) from the environment. Then plants release oxygen (O2) into the < >A、airB、controlC、dangerousD、temperatureE、water>. Humans need oxygen to live.