sustain vs prolong

sustain and prolong both are verbs.

Word	Noun	Adjective	Verb	Adverb
sustain	No	No	Yes	No
prolong	No	No	Yes	No

As verbs, sustain and prolong are synonyms defined as:

Other synonyms of sustain include keep up.

sustain (verb)	prolong (verb)
undergo (as of injuries and illnesses)	lengthen in time; cause to be or last longer
establish or strengthen as with new evidence or facts	lengthen or extend in duration or space
admit as valid
supply with necessities and support
provide with nourishment
be the physical support of; carry the weight of
lengthen or extend in duration or space