Yesterday a traffic accident happened the boy in the street.
A:about
B:to
C:at
D:on
西北地区的主要自然特征 ( )
Who is he ________ for?
已知:如图,BO平分∠ABC,CO平分∠ACB,且MN∥BC,设AB=12,AC=18,则△AMN的周长是( )