因为23x=12y,
所以x:y=12:23=3:4,
故答案为:4.
Just after putting away the dishes, _______.
A.the doorbell was rung
B.mother heard the doorbell ring
C.someone knocked at the door
D.the doorbell rang loud
物流技术及装备的应用和普及程度是物流系统水平先进与否的主要标志。