Relative to fetuses with a nasal bone, those without a nasal bone were estimated to have about 150-times the risk of having trisomy 21.是什么意思_Relative to fetuses with a nasal bone, those without a nasal bone were estimated to have about 150-times the risk of having trisomy 21.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句