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
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The word "they' in line 8 refers to ______.
A. gasses
B. volcanoes
C. steam vents
D. rocks
The passage suggests that oxygen remained in the atmosphere because ______.
A. it was caused by outgassing
B. it was heavier than hydrogen
C. hydrogen became trapped in limestone
D. rays from the sun created equal amounts of hydrogen and oxygen ______.
The phase “At any rate ”in line 26 is closest in meaning to ______.
A. regardless
B. in addition
C. although unlikely
D. fortunately
What is said about express mail？
A. It is very reliable.
B. It is quick.
C. It costs less.
D. It guarantees safe delivery.
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