A.老年人占據(jù)人口比例大B.獨(dú)居老人和空巢老人增速加快C.獨(dú)居老人和空巢老人比重增高D.生育率降低
A.經(jīng)濟(jì)增長(zhǎng)B.社會(huì)進(jìn)步C.總?cè)丝谠鲩L(zhǎng)D.人口流動(dòng)