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.
查看答案
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.
According to paragraph 3, how do ectoparasites survive？
A. They live in mold and mildew on their hosts.
B. They digest food in the intestines of their hosts.
C. They live on the nutrients in their bacterial hosts.
D. They inhabit the outside parts of their hosts.
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