-- Are these _______ all from No. 2 Middle School?

-- Yes. They often _________ their free time to help the old here.

A．volunteers; volunteers

B．volunteer; volunteers

C．volunteers; volunteer

D．volunteer; volunteer

实数a=2012³﹣2012，下列各数中不能整除a的是 [ ]

A．2013

B．2012

C．2011

D．2010