Japanese - I speak too fast.
English - I speak too carelessly.
French - I need more practice.
German - I need a bigger vocabulary.
Latin - I keep it for my pleasure in the future.
Greek - It's all Greek to me.
C, Emacs Lisp, Common Lisp, Prolog, etc.
LaTeX, html, texinfo, etc.
Progressive rock, acoustic guitar with virtuosity
e.g.,
U.K.,
King Crimson,
Yes,
Gentle Giant,
Super Guitar Trio
and others.
`The most important thing in music is technique.'
It's bad for the health.