In1990,over100countriessigned 61 internationalagreemen...
問題詳情：In1990,over100countriessigned61internationalagreementtomakeitillegaltobuyorsellivory,whichismainlyusedforjewelry.Mostivoryismadefromthetusks（象牙)ofAfricanelephants.Thesetusksare 62 ...