Defective is an adjective and doesn't have tenses. Only verbs have tenses.
"must" is an example of a defective verb. It has only the present tense. To get the meaning of the past perfect tense of must, you have to say something like"had been required" or "had been obligated".
the past tense of am is was and the past tense of has is had
The past tense of get is got. For isn't a verb and so doesn't have a past tense. The past tense of has is had. Had is already the past tense. The past tense of have is had.
Was and were are both the past tense of be. The present tense is: I am he is you are they are The past tense is: I was he was you were they were
The past tense of "will" is "would". The past tense of "to be" is "was" or "were".
Wrote is past tense. It is the past tense of write.Wrote is already a past tense.
The past tense of "finish" is "finished". The past tense of "be" is "was" (singular) or "were" (plural).
The past tense is schooled. The past continuous tense is 'was/were schooling'.
Simple past tense. Past perfect tense. Past continuous tense.
Existed is the past tense. The past perfect tense is had existed.
Met is the past tense of meet, and you can't have past tense of something that is already past tense.
Wore is past tense. The present tense is wear.