单项选择题

We can infer from Dr Myers and Dr. Worm's paper that ______.

A．the stock of large predators in some old fisheries has reduced by 90%
B．there are only half as many fisheries as there were 15 years ago
C．the catch sizes in new fisheries are only 20% of the original amount
D．the number of larger predators dropped faster in new fisheries than in the old

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单项选择题

The extinction of large prehistoric animals is noted to suggest that ______.

A．large animal were vulnerable to the changing environment
B．small species survived as large animals disappeared
C．large sea animals may face the same threat today
D．slow - growing fish outlive fast - growing ones

单项选择题

The text suggests that immigrants now in the U. S. ______.

A．are resistant to homogenization.
B．exert a great influence on American culture.
C．are hardly a threat to the common culture.
D．constitute the majority of' the population.