Do 食べないです and 食べなかったです have the same level of politeness as 食べません and 食べませんでした have?


Up to now, I am still confused with this very basic grammar.

# Non-past

  * Informal : 食べる (+) and 食べない (-)
  * Formal : 食べます (+) and 食べません (-)

# Past

  * Informal : 食べた (+) and 食べなかった (-)
  * Formal : 食べました (+) and 食べませんでした (-)

Surprisingly, in order to upgrade the level of politeness (or formality), we
can only append です to the negative of the informal form.

  * Non-past: 食べないです
  * Past: 食べなかったです

The following are not allowed (I don't know why):

  * Non-past: 食べるです
  * Past: 食べたです

# Questions:

  1. Does 食べないです (and 食べなかったです) have the same level of politeness as 食べません (and 食べませんでした) has?

  2. Bonus question: Why 食べるです and 食べたです are not allowed?




1.I think so because a verbal auxiliary "です、ます" which represent formal lines
is used for them.

2.Because a verbal auxiliary "です" is set after 連体形 of the verb + の and 体言(noun
and pronoun).




1.I think so because a verbal auxiliary "です、ます" which represent formal lines
is used for them.

2.Because a verbal auxiliary "です" is set after 連体形 of the verb + の and 体言(noun
and pronoun).

