Necessary is not a verb and does not have participle forms.
Past participle.
The word 'vanished' is the past participle, past tense of the verb 'to vanish'; the past participle of the verb is also an adjective, for example, a vanished species.Noun forms for the verb 'to vanish' are 'vanisher' and 'vanishment'.
No, the word 'understood' is the past participle, past tense of the verb to understand. The past participle of the verb also functions as an adjective.The abstract noun form of the verb to understand is the gerund, understanding.
The word 'dispersed' is the past participle, past tense of the verb to disperse. The past participle of the verb also functions as an adjective.The noun forms of the verb to 'disperse' are disperser, dispersal, and the gerund, dispersing.
The word 'lost' is the past participle, past tense of the verb to lose. The past participle of the verb also functions as an adjective.The abstract noun related to the verb lose is loss.
The past participle of "do" is "done." The past participle of "have" is "had."
The past participle of "am not" is "have not been."
The past participle of "do" is "done."
The past tense of "have" is "had," and the past participle is also "had."
The past participle of the word "have" is "had."
The past participle of "will" is "willed."
The past participle of "am, are, is" is "been."
The past participle is thought.
The past participle of "to" is "been." The past participle of "be" is also "been."
Being is the present participle. The past participle is been.
The past tense and the past participle is "answered".
Present participle: hiding Past: hid Past participle: hidden