单项选择题

Useful drugs are made from inorganic substances or are plant and animal by-products.（）

A．materials
B．derivatives
C．chemicals
D．ingredients

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单项选择题
Although she scrubbed the old pot thoroughly, she could not make it look completely clean.（）

A．disinfected
B．scoured
C．rinsed
D．scratched
单项选择题
Some political analysts feel that the power of the northeastern United States is on the wane.（）

A．old-fashioned
B．dwindling
C．stabilizing
D．forgotten
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