单项选择题

Nowhere in nature is aluminum found free, owing to its always ______ with other elements, most commonly with oxygen.

A．being combined
B．having combined
C．to combine
D．combined
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单项选择题
If the task ______ by the end of this year is delayed, the company will be under punishment.
A．being completed
B．is completed
C．to be completed
D．completed
单项选择题
Few people know him, ______ .
A．do they
B．don't they
C．doesn't few
D．don't few
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