(Number)しか～ない

About

The (number)しか～ない pattern can be used to express that there is a low or insufficient quantity of something. If the negative verb is ある, しか and ない (or the polite ありません) will be attached directly:

E.g. 2個こしかありません。
"There are only two."

But often a different negative verb will separate しか from ない:

E.g. 二ふたつしか食たべていない。
"I've only eaten two."

Compared to the very similar ～もない, (number)しか～ない expresses a specific quantity.

Summary

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  (Number)しか～ない expresses that there is a low or insufficient quantity of something

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  (Number)しか～ない always provides a specific quantity