单项选择题

A considerable amount of time and money has been invested in ______ this system.

A．defining
B．implying
C．reducing
D．perfecting
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单项选择题
I don't know how to interpret her remark. I think it was deliberately ______.
A．distinct
B．ambiguous
C．suspicious
D．invisible
单项选择题
The Barbie doll comes with a whole range of ______ that you can dress her in.
A．outlooks
B．outlines
C．outskirts
D．outfits
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