单项选择题

It is implied in the passage that ______.

A．sugar planter imported mongooses to control rats
B．man should never kill animals
C．man has complete control over nature
D．upsetting the balance of nature can be troublesome

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热门试题

单项选择题

The phrase balance of nature in the first line means ______.

A．reducing the population of.predators and parasites
B．keeping the right number of animals for the right amount of food
C．keeping the ratio of small game to predators
D．driving animals to mass migrations

单项选择题

The fact that the number of one kind of animal may have much to do with that of other animals

A．is not recent knowledge
B．has just been learned
C．has not proved yet
D．is not important now