单项选择题

Economies, several courses of which I have taken thus far, ______ to be difficult but useful for almost all students.

A．prove
B．proves
C．have been proved
D．are proved
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单项选择题
The bedroom is in perfect condition, ______ a few scratches on the wall.
A．except
B．excepting
C．except for
D．except that
单项选择题
All those youngesters will become ______ in ten years.
A．growns-ups
B．growns-up
C．grown-up
D．grown-ups
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