2. To test whether plants are a sot，roe of methane，the scientists created
A a oxygen-free environment.
B an environment with the same concentration of oxygen as the Earth has.
C a carbon dioxide-free environment.
D an environment filled with the greenhouse gas.
3. Which statement is true of the methane emissions of plants in the experiment?
A The lower the temperature，the higher the amount of methane emissions.
B I.iving plants release less methane than dried plants at the same temperature.
C When exposed to sunlight，plants stop releasing methane.
D The higher the temperature，the greater the amount of methane emissions.
4. Which of the following about methane is Not mentioned in the passage?
A Plants growing in soil release methane.
B Plants growing in water release methane.
C Soil microbes consume methane.
D Microbes in plants produce methane.
5. What is the beneficial point of some microbes consuming plant-produced methane?
A Methane becomes less poisonous.
B Methane is turned into a fertilizer.
C Less methane reaches the atmosphere.
D Air becomes cleaner.