介绍:
“black letter day”refers to the day we are not so lucky and happy!
For example:
Today is really a black letter day for me, I locked myself outside the door!
“black sheep”
In the English language, black sheep is an idiom used to describe an odd or disreputable member of a group, especially within a family.
起初在英语中它指的是害群之马。
The term stems from the genetic effect in sheep whereby a recessive gene occasionally manifests in the birth of a sheep with black rather than white coloring; these sheep stand out in the flock.
这个词语最初用来指在一群出生的白马中有一匹马由于隐性基因，出生时黑马，和其它马的颜色不用，比较与众不同；
The term has typically been given negative implications, implying waywardness. It derived from the atypical and unwanted presence of other black individuals in flocks of white sheep.
人们大多用它的贬义，用它来指那些不合群的人。
In psychology, the black sheep effect refers to the tendency of group members to judge likeable ingroup members more positively and deviant ingroup member more negatively than comparable outgroup members.
在心理学中，这种难以预料的竞争者或出人意料的优胜者所产生的心里效应现象就叫做黑马效应。
