black stain

基本解释

In 1873 the Italian scientist Camillo Golgi developed a black stain to highlight the micron-thin neural strands.
1873年，意大利科學家卡米洛·高爾基（Camillo Golgi）發明了一種黑色染料，可以對極細的神經索進行染色。
In a painter's house, I saw a very special painting which was a piece of munted white paper, on the left middle of which there was a black stain.
在畫家的房子裡，我看到一幅極其特別的畫：那是一張經過裝裱的白紙，但在其左側正中有一個黑點。
baicaoyuanrena.blog.163.com
Meanwhile our roaring creek was still at it, but thinner and more quiet now, running from the cliff face itself a mile up the valley in a big black stain I could see in the gray rock.
於此同時我們那轟鳴的谿流依然固我，但它如今變得瘦弱淡靜，從一裡外山穀上灰暗石頭中我能看到的一個黑色大汙點，朝崖麪飛奔逃離自己。
blog.sina.com.cn

They were, understandably, deeply offensive to black Americans and all others who regard segregation as a terrible stain on this Nation's history.
CENTERFORSECURITYPOLICY: Dustbin Durbin