Could is the past form of can. (Sometimes was/were able to is used instead of could.)
The past tense of the verb 'am' is 'was' or 'were.' The verb 'am' is derived from the verb 'to be.'
The past tense of "do" is "did."
By is not a verb and does not have a past tense. Buy is a verb, and the past tense is bought.
The past-tense verb for "be" is "was" or "were" depending on the subject.
The past tense of the verb "promise" is "promised."
"Shook" is the past tense of the verb, "to shake".
The past tense of the verb "take" is "took."
reside is the verb. Resided is the past tense.
The abbreviation for the past tense verb is "past."
Inactive is not a verb and does not have a past tense. Inactivate is a verb, and the past tense is inactivated.
Slept is the past tense of the verb sleep, so there is no past tense for it.
The past tense of the verb "stink" is "stank."