有机物燃烧生成8.8gCO2和5.4gH2O,则一定含有C、H元素,其中n(CO2)= 8.8g 44g/mol =0.2mol,n(C)=0.2mol,m(C)=0.2mol×12g/mol=2.4g,n(H2O)= 5.4g 18g/mol =0.3mol,n(H)=0.6mol,m(H)=0.6g,且n(C):n(H)=0.2mol:0.6mol=1:3,由于2.4g+0.6g=3.0g<6.4g,则一定含有氧元素,故选D.