单项选择题

Both tea and coffee contain caffeine, an odorless, colorless ____________ that is soluble in water and in alcohol.

A．substance
B．material
C．matter
D．object
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单项选择题
The light bulb in the bathroom burned ____________ and Father put in a new one.
A．off
B．down
C．out
D．away
单项选择题
Many birds and insects can build ____________ nests to provide shelter for their young.
A．glorious
B．elaborate
C．splendid
D．appropriate
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