By comparison , the fertility rate in developed countries has been stable, or fall ing .
By comparison , the fertility rate in developed countries has been stable, or fall ing .
与此形成对比的是，发达国家的出生率持续稳定或出现倒退。
By comparison , the fertility rate in developed countries has been stable, or fall ing .
与此形成对比的是，发达国家的出生率持续稳定或出现倒退。