已知:菱形ABCD中,对角线AC与BD相交于点O,OE∥DC交BC于点E,AD=6cm,则OE的长为( )
A:6cm
B:4cm
C:3cm
D:2cm
两个有理数的和为零,则这两个数一定是( )
用所给词的适当形式填空
The bus ride is not ____ (bore) , because I can talk to my classmates.
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