Sharpened is a verb. It describes the action of making something sharp.
sharpened
The part of speech for "answer" is a noun.
part of speech
The part of speech for this particular word is a noun.
what part of speech is beneath
adverb
what part of speech is work
Your canine teeth can be sharpened by going to your dentist, where he/she will probably add a contour in place, but if you mean 'sharpened' like a pencil sharpened, then talk to your dentist about that.
The past tense of sharpen is sharpened and the past participle is also sharpened.
The part of speech for "unfamiliar" is an adjective.
The part of speech for "explicit" is an adjective.
The part of speech for "buried" is a verb.