８課

Both はずがない and わけがない are used to express strong disbelief or impossibility in Japanese.

とは限らない is used to express that something is not always true or does not necessarily apply in all cases.

All three of these expressions—わけではない, というわけではない, and のではない—are used to indicate partial negation or clarification in Japanese.

ないことはない is a phrase used to express a slight possibility or reluctant affirmation.

ことは～が is used to acknowledge that something is technically true or possible, but downplays the significance or expresses limitations.