собака =>собаки
  кошка  =>кошки,
          not Ы ? why?

  雷同:
  Here are the rules for
    и, а, у vs.
    ы, я, ю:

  use only И, not Ы, after к, г, х/ ж, ш, щ, ч
  use only А, У after к, г, х/ ж, ш, щ, ч and ц (and never use Я, Ю after them)

  К, Г, Х are called velar consonants (i.e. made in the back) and
  Ш, Щ, Ж, Ч are often called hushes.
  
  The latter do not show palatalized/non-palatalized pairs in modern Russian,
  so the spelling rule does not affect pronunciation anyhow. It's just a convention.

【 在 limp 的大作中提到: 】
: Day 1
:     六格
:     Nominative (subject)
: ...................
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FROM 222.90.58.*