单选题 It's commonly acknowledged that infant mortality has declined because of recent medical ______ and a higher standard of living.

【正确答案】 B

【答案解析】[分析] 形近识别 A．recoveries恢复，痊愈；B．discoveries发现，发现的东西；C．coverage覆盖；D．leverage杠杆作用，手段，影响力。本句意为：人们都承认婴儿的死亡率下降是因为近代的医学发明和生活水平的提高。因此选项B为答案。