Please because this is a reading room.
A:quiet
B:to be quiet
C:be quiet
点O是平行四边形ABCD的两条对角线的交点,则AO→+OC→+CB→等于( )
某同学进入泳池前以为池水很浅,踩下去后却有一种“踏空”的感觉,则水的实际深度要比看上去的深一些,其原因是( )