如图,在菱形ABCD中,对角线AC与BD相交于点O,AC=8,BD=6,OE⊥BC,垂足为点E,则OE= ____.
以下减小噪声的措施中,属于在传播过程中减弱的是( )
I'd like to join the school volunteer project, but I'm not sure ______.