ことだ-ийн хэл зүйн хайлтын үр дүн

ことだから

Shows a typical trait or characteristic of A

[事「こと」]だ

A is necessary/good (offering advice/suggestion)

とは/というのは

Defines a term/phrase A as B; The meaning of A is B

までだ/までのことだ

Only A (will be done)