听力文本

Historic Kilogram Weight Measure to Be Replaced
For nearly 130 years, the world's scientists have used a singular small, metal cylinder to define the exact weight of a kilogram. But that is about to change.
The cylinder was made in 1889 of platinum and iridium metals. It is called the Grand K. The International Bureau of Weights and Measures, or BIPM, keeps the object at its headquarters near Paris. Many safeguards protect the Grand K. In fact, it takes three specially chosen people to open the container that holds the cylinder. They must each release separate locks at exactly the same time to do so.
The Grand K has served as the official world measurement tool for weight in kilograms. All modern mass measurements have been based on the Grand K.
There are seven main units of official measure. These include the meter for length, and the second for time. Other units measure things like electrical current or amounts of a substance.
Currently, the kilogram is the only measure based on a physical object. The meter used to be represented by a singular metal stick. In 1983, scientists decided that a meter would be defined by the speed of light. Light speed is constant. Light always takes the same amount of time to travel one meter.
The Grand K was only rarely — and always extremely carefully — removed so that other kilos sent from around the world could be compared to it.
But even such rare contact does not fully protect the Grand K and its mass. It is still affected by its environment. This can be a problem when using it as the single exact weight measurement tool.
Ian Robinson is an engineering specialist at Britain's National Physical Laboratory. He told Reuters that pollutants in the atmosphere can easily add weight to the historic measuring tool.
"When you just get it out of the vault, it's slightly dirty," Robinson said. "But the whole process of cleaning or handling or using the mass can change its mass."

Now, officials at the BIPM believe the time is right to change the kilogram standard, to make it fit better in today's technology-driven world. So on November 16, scientists from around the world will gather in Paris to approve replacing the Grand K with a new standard.
BIPM's director, Martin Milton, told the Associated Press he does not see the event as a sad development, but as "a moment of celebration." He says this is because it will be the last world measurement standard to "finally be replaced by new innovation."
The Grand K is to be replaced by a new definition based on a complex physics formula called "Planck's constant." This process can measure the mass of an object using electromagnetic force. The method will permit scientists to correctly measure an exact kilogram without comparing it directly with the weight of a physical object.
Milton says changes in drug and chemical production now require new ways to measure much smaller amounts of material. He says a kilo is fine for weighing things like potatoes, where extreme exactness is not necessary.
"But it's not the right weight for many applications in demanding science and industry," he said.
Scientists have spent years developing the new definition to make sure the change goes smoothly.
Although the time has finally come to change the Grand K, Milton says the system has served humanity well and proved man's ability to unite for science. "It's been called a great work of peace, actually, because it's one of the areas where all of the states of the world come together with absolutely the same objective."
I'm Bryan Lynn.

重点解析

重点讲解：
1. be about to do sth. 即将（做…）的；快要（发生…）的；
I was just about to ask you the same thing.
我刚才正要问你同一件事情0~1Xzp4R&7-(~%dHv。
2. be based on 以…为基础；
Many pictures have been based on simple geometric designs.
许多画都是基于简单的几何图案S9V[#|vt[3dNX。
3. used to do sth. 过去常常；过去曾；
We used to go sailing on the lake in summer.
从前的夏天，我们经常泛舟湖上uX.#43A[0vZ[f。
4. replace A with B 用B代替A；
In the long-term it may be necessary to try and replace the old habit with a new one.
长远来看，尝试用一个新习惯代替旧习惯可能是必要的xLh7T_|D)r&Zu.s9mX&m。

参考译文

国际标准公斤实体"大K"将被取代
近130年来，全球科学家一直用一个小金属圆柱来确定一公斤的精确重量)o;ZytFoJyVaP@%。但是这即将改变Ynx7adBaGJwjvTZ。
这个圆柱体在1889年由铂铱合金制成,X2w7GVQ-x~K。其被称为“大K”L9-)G2.TCaf3。国际度量衡局（简称BIPM）将这一圆柱体保存在其位于巴黎附近的总部yygeTe_VL.hmPcT。有许多防护措施为“大K”提供保护W);%#&r%&1n|gp。实际上，需要3个特别挑选出的人才能打开存放“大K”的钟罩PXT%x*X9yWqVsCv。这三人每人持一把钥匙，三把钥匙必须在同一时间解锁fkW15Jr)vscsIC&egF。
“大K”是全球衡量公斤重量的官方工具NtVW@y4D~G)FV0iVd!43。所有现代质量测量工具都以“大K”为基础vfG-Rs9(*8C。
官方测量标准有7个主要单位#f1iiE.YtEAD。包括长度单位米和时间单位秒cQFfTSK)fFHHOvvW*。其他测量单位还包括电流单位和物质的量的单位G3NYl8X1BiA-=MLA。
目前，公斤是唯一依赖于物理实体的测量单位k0sap(R&C4ie]^U-yz。过去，米曾用一根金属棒来代表Gcg;uQ]qjC!2。1983年，科学家决定用光速来定义米]u*giF3VIl)z7KuF.。光速是常数2cZ.Gw[*QtPS7G3-。光一直以同样的速度前进lAZ|.1&z7x#MwtNI0。
“大K”很少移动，即使移动也一直极其小心，所以世界各地发布的其他公斤测量单位可以与“大K”进行比较6FD+c&I%+5&(!9oG。
但是，即使很少接触，也没能完全保护“大K”及其质量oH]XOoGgV)。它还是受到了周围环境的影响j,wpE)iQW!AQ^nEMv#。这在将“大K”用作单一且精确的重量衡量工具时会成为问题A9Qr^kQrArh。
伊恩·罗宾逊是英国国家物理实验室的工程专家LfQ]UGaqj]~)。他对路透社表示，大气中的污染物可以很容易地增加这一具有历史意义的衡量工具的重量5upzez)m6h8q(z!fQ。
罗宾逊说，“当你将‘大K’从地窖中取出来时，它会有些脏!&STGf#*yV。但是清洁或处理或使用质量的整个过程会改变其质量nySSY8&d;9jegJ3Q。”
国际度量衡局官员认为，现在是时候改变公斤测量标准了，目的是使测量标准更适应当今以技术驱动的世界ims102TPgDCOf。因此，来自世界各地的科学家将于11月16日聚集巴黎，通过用新标准取代“大K”的提议]NZKs&wF#F。
国际度量衡局局长马丁·米尔顿对美联社表示，他认为这不是令人难过的发展，而是“庆祝的时刻”,Wp2sQkP.kY1-ugy*%。他说，这是因为“大K”将是世界上最后一个“终于被新型创新取代”的衡量标准-WhTmJFT6pe%n]0o。
“大K”将被普朗克常数取代，普朗克常数是一种以复杂的物理公式为基础的新定义ZI(Y#NZY;=c%。普朗克常数可以衡量使用电磁力的物体的质量~YD;x~G_zLiOvFFF%Y。这种方法使科学家可以在不用和物理实体的重量进行直接比较的情况下，准确地衡量公斤数tN1dgZ]dV4,B。
米尔顿表示，药物和化工生产的变化需要新方法，以测量小得多的材料W-~0Un3a(lYk~jZL,1。他说，公斤在测量土豆等东西时没有问题，因为这些东西不需要极度精确性M29@~.|B4-+*Q(O~J]#T。
他表示，“但是对要求严苛的科学与工业中的许多应用来说，公斤已经不适用了5y1^RZwQ~ri!A2Iz;1。”
科学家在开发新定义上花费了数年时间，目的是确保改变能顺利进行]+qI!-oq^81LcyL。
米尔顿表示，虽然改变“大K”的时刻最终还是来临了，但是这一系统很好地为人类进行了服务，而且证明了人类联合科学的能力7ruW9V=[c|yL-y5^ruu0。“实际上，它被称为伟大的和平工作，因为它是使世界上所有国家以绝对相同的目标团结起来的其中一个领域TAa!AW+(o[-Pk。”
我是布莱恩·莱恩Y|MO9J3UDBZp#aU_z。

译文为可可英语翻译，未经授权请勿转载！