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单项选择题

When our university laboratory bought this microscope we were given a one year's ______.

A．reservation
B．security
C．proof
D．guarantee
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热门试题

单项选择题A．soB．muchC．ratherD．too

A．so
B．much
C．rather
D．too

单项选择题A．respectivelyB．eachC．allD．more

A．respectively
B．each
C．all
D．more