单项选择题

The structure of aircraft ______ all the time.

A．is being changed
B．has been changed
C．is been changed
D．is being changing
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This page need ______ again.
A．being checked
B．checked
C．to check
D．to be checked
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As you've never been there before, I'll have someone ______ you the way.
A．to show
B．show
C．showing
D．showed
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