如图,平行四边形ABCD的对角线交点是O,则下列等式成立的是( )
体育委员带了500元钱去买体育用品,已知一个足球a元,一个篮球b元,说明代数式500﹣3a﹣2b表示的意义.
Some sports that were part of the Olympics in the past have been removed to __________ new sports which are more popular.