Question

he would never fail in anything he might undertake . (fail noun form )

Answer 1

Hey dear!!
________
 
You have asked to modify the sentence using noun form of 'fail'.

here is the sentence:

He would never be a failure in anything he might undertake.


Explanation- to use the non-form 'failure' an auxiliary verb 'be' has been used here to make the sentence grammatically correct and convey proper meaning.

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Answer 2

Answer:

He would never be a failure in anything he might undertake.