請將下面這段話翻譯成英文：

　　計量，古稱度量衡，是實現(xiàn)單位制統(tǒng)一，保證量值準(zhǔn)確可靠的活動，是現(xiàn)代國家經(jīng)濟、科技、社會發(fā)展的重要基礎(chǔ)。計量歷史悠久，關(guān)系國計民生。公元前221年秦朝建立，秦始皇統(tǒng)一度量衡，成為中國古代統(tǒng)一計量制度的里程碑。1875年5月20日《米制公約》的簽署，開辟了全球范圍內(nèi)推行國際單位制的近代計量新紀(jì)元。以量子物理為基礎(chǔ)的現(xiàn)代計量科學(xué)技術(shù)的研究與應(yīng)用，為人類文明發(fā)展提供了更加精準(zhǔn)的現(xiàn)代計量技術(shù)保障。1999年第21屆國際計量大會決定：自2000年起，每年5月20日為“世界計量日”。2015年世界計量日的中國宣傳主題與國際主題一致，為“計量與光”。

　　參考譯文：

　　Measurement, which is called metrology in ancient times, is the important foundation of social development of the modern countries' economy, science and technology. It has a long history and plays an important role in national welfare and the people's livelihood. Established in 221 BC, in the Qin dynasty, Qinshihuang unified weights and measures, and became a unified system for the measurement of milestone in ancient China. On May 20th, 1875, the signing of the convention on metric, opened up a worldwide to implement new era of modern international system of units of measurement. Based on quantum physics, research and application of modern measurement science and technology, provides more accurate modern metrology technical support for the development of human civilization. In 1999, the 21st international conference on measurement made a decision that since 2000, May 20 is for "World Metrology Day". China's propaganda theme of 2015 is in line with international theme for