In paragraph 7, why does the author use the example of the Acacia tree？
A. To demonstrate how ants survive by living in trees
B. To explain how two species can benefit from contact
C. To show the relationship between plants and animals
D. To present a problem that occurs often in nature
查看答案
The word prominent in the passage is closest in meaning to
A. weak
B. important
C. small
D. new
The word derives in the passage is closest in meaning to
A. requests
B. pursues
C. obtains
D. rejects
The word stable in the passage is closest in meaning to
A. visible
B. active
C. constant
D. strong
According to paragraph 8, how does bacteria affect beans and clover？
A. It causes many of the plants to die.
B. It limits the growth of young plants.
C. It supplies nitrogen to the crops.
D. It infects the roots with harmful nodules.
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