【单选题】Slang(俚语) is one of those things that everybody can recognize and nobody can define(下定义). Not only is it hard to wrap slang in a definition, it is also hard to distinguish (区别)it from such similar thi...
A.
Nobody has defined and recognized slang, although they are used by a generation after another generation.
B.
Slang tends to be transient though they have found their way in dictionaries.
C.
Having difficulty in defining slang and telling slang from similar things, people still use slang frequently.
D.
Slang can be totally beyond the understanding of the old.