They found traces ranging from less than one-hundredth of a microgram to more than 1,000 micrograms, or about one-30,000th of an ounce.是什么意思_They found traces ranging from less than one-hundredth of a microgram to more than 1,000 micrograms, or about one-30,000th of an ounce.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句