Which of the following does the passage mention as necessary for both the production of oxygen by photodissociation and the production of oxygen by plants？
A. Water
B. Hydrogen
Carbon dioxide
D. Nitrogen
查看答案
The word "enveloped" in line 6 is closest in meaning to ______.
A. surrounded
B. changed
C. escaped
D. characterized
The author uses the word "Or" in line 25 to
A. criticize the previous suggestion
B. provide unrelated information
C. propose a similar idea
D. suggest an alternative
According to the passage, outgassing eventually led to all of the following EXCEPT ______.
A. increases in the carbon dioxide content of sedimentary rocks
B. the formation of bodies of water
C. decreases in the level of nitrogen
D. the formation of clouds
The word "they' in line 8 refers to ______.
A. gasses
B. volcanoes
C. steam vents
D. rocks
微信支付 
支付宝支付