题目

By the YouthWhen we were scared, sad and helpless, you gave us courage, warmth and hopes. When we had to stay at home to keep away from the illness, you, workers, helped us buy living things;Leaving your children behind, you worked in the neighborhood every day, you never complained but smiled the whole day. When we needed all kinds of materials, you, drivers, drove them there without thinking twice;Running on the streets, between the cities, you made sure things went well as usual.When we had coughs or fevers, you, ▲, tried your best to save our lives;Looking after the patients in the hospi如图，平行四边形ABCD的对角线AC、BD相交于点O，下列结论正确的是A．SABCD=4S△AOBB．AC=BDC．AC⊥BDD．ABCD是轴对称图形