纯生啤酒为什么叫做draft

draft:a serving of drink (usually alcoholic) drawn from a keg

drawn from 得到(提取)

keg: [ keg ]

n. 三十加仑以下的小桶

draft beer = draught beer:

生啤酒

可能跟啤酒的历史起源有关，你去查查吧，正好让我也长长见识。。

Draught beer (also known as draft beer or tap beer) has several related though slightly different understandings. The majority of references to draught beer are of filtered beer that has been served from a pressurised container, such as a keg or a widget can[citation needed]. A narrower meaning is beer that is served from a keg (or tap), but not from a can, bottle or cask, is also used. A more traditional definition is beer that is served from a large container, which could be either a keg or a cask. The different understandings may at times overlap and cause confusion. Some traditionalists object to the more modern use of the word when applied to canned beer. The slight usage differences of the term is due to the history and development of beer di