//=== https://en.wikipedia.org/wiki/Ton
ton vs tonne
Where confusion is possible, the 2240 lb ton is called "long ton" and the 2000 lb ton "short ton";
the tonne is distinguished by its spelling, but usually pronounced the same as ton,
hence the US term "metric ton".
In the UK the final "e" of "tonne" can also be pronounced (/ˈtʌnɪ/), or "metric ton" when it is necessary to make the distinction.
Ton is derived from the tun, the term applied to a cask of the largest size.
This could contain a volume between 175 and 213 imperial gallons (210 and 256 US gal; 800 and 970 l), which could weigh around 2,000 pounds (910 kg) and occupy some 60 cubic feet (1.7 m^3) of space.
The origin for the word ton comes from ancient Greek θύννος (thúnnos, tuna fish).
In the United Kingdom the ton is defined as 2,240 avoirdupois pounds (1,016 kg).
This is equivalent to 20 hundredweight, a hundredweight being eight stone, and a stone weighing 14 pounds.
From 1965 the UK embarked upon a programme of metrication and gradually introduced metric units,
including the tonne (metric ton), defined as 1000 kg (2,204.6 lb).
In the United States and formerly Canada[4] a ton is defined to be 2,000 pounds (907 kg).
//=== https://zh.wikipedia.org/wiki/%E8%8B%B1%E5%99%B8
英噸（ton）或噸是英制單位，使用地區主要為英國、美國與一些英联邦國家。其和公吨（tonne或metricton）有所區別。
廣義的英噸又可分為長噸（long ton）和短噸（short ton）。
長噸：在英國較為常用，為狹義的「英噸」，在英國常直接稱為「噸」（ton）。
短噸：在美國較為常用，又稱「美噸」
單位換算[编辑]
1長噸 = 2,240磅。
1短噸 = 2,000磅。
公制換算1長噸 = 1.0160469088公吨 = 1016.0469088公斤；和公吨只差不到2%。
1短噸 = 0.90718474公吨 = 907.18474公斤。
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