〜とは限らない（とはかぎらない）

About

The ～とは限かぎらない pattern is used to express that something is "not guaranteed to be the case; not necessarily the case; not always X".

～とは限かぎらない can attach directly to verbs, い-adjectives, nouns, and な-adjectives. Nouns and な-adjectives may optionally attach using だ for additional emphasis.

E.g. イケメンなら誰だれでもモテるとは限かぎらないよ！ "Being handsome does not guarantee that you'll be popular!"

E.g. 日本人にほんじんが話はなす日本語にほんごがいつも正ただしいとは限かぎりません。 "The Japanese that Japanese people speak is not necessarily always correct."

～とは限かぎらない is commonly paired with words such as 「いつも・誰だれでも・必かならず」, as well as the grammar points ～からといって and 必かならずしも.

E.g. イタリアに5年ねん住すんでいるからといって、イタリア語ごを話はなせるとは限かぎらない。 "Simply because they've lived in Italy for five years, doesn't necessarily mean that they can speak Italian."

E.g. 経験者けいけんしゃだからといって何なんでもできるとは限かぎらない。 "Simply because they're experienced doesn't necessarily mean that they can do anything."

The 「Xないとも限かぎらない」 pattern is used to put more focus on the possibility that "X might be true".

E.g. プロだからって、失敗しっぱいしないとも限かぎらないよ。 "Just because they're a pro doesn't mean they couldn't make a mistake."

Summary

• 

  The ～とは限かぎらない pattern is used to express that something is "not guaranteed to be the case; not necessarily the case; not always X"

• 

  ～とは限かぎらない can attach directly to verbs, い-adjectives, nouns, and な-adjectives

• 

  The 「Xないとも限かぎらない」 pattern is used to put more focus on the possibility that "X might be true"