The word it in the passage refers to
A. ice
B. soil
C. moon
D. solar system
查看答案
All of the following are cited as reasons why civilizations developed EXCEPT
A. Religious practices unified the population.
B. The management of water required organization.
C. A major climate change made living in groups necessary.
D. Extra food resulted in the expansion of population centers.
A．profitableB．voluntaryC．accidentalD．compulsory
A. profitable
B. voluntary
C. accidental
D. compulsory
D.The relationship between a parasite and a host will evolve over time. The word tolerate in the passage is closest in meaning to
A. permit
B. oppose
C. profit
D. avoid
Which of the following statements about the water on Venus is true？
A. The water evaporated because of the high temperatures.
B. The water became frozen in the polar regions.
C. Only a little water is left in small lakes on the surface.
D. Rain does not fall because there is no atmosphere.
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