单项选择题

The sharp rise of the snow geese population is mainly caused by______.

A．lack of natural enemies
B．great care of wildlife preservationists
C．favorable conditions in their winter habitat
D．changes in their migration patterns
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单项选择题
According to the author, if the marshes are destroyed,______.
A．the snow geese will be in danger
B．the agriculture of the area will suffer
C．the Canada geese will replace the snow geese
D．the snow geese may move to breed in Minnesota
单项选择题
According to the passage, for which of the following reasons are the late seventeenth and early eighteenth-century Chinese records important
A．They contradict the theory of the Maunder minimum.
B．They suggest that the Maunder minimum cannot be related to climate.
C．They verify the existence of a span of unusual cold worldwide during the Maunder minimum.
D．They show that the European observations are of dubious statistical significanc
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