Theater is a noun and so doesn't have a past tense. Only verbs have a past tense.
'Theatre' is a noun, it doesn't have a past tense.
plays is a present tense and its past tense is played.
The past tense is danced.
The past tense of entertain is entertained.
Performed is past tense. The present tense is perform, and the future tense is will perform.
The past tense is volunteered.
'Theatre' is a noun, it doesn't have a past tense.
The past tense is occurred.
The past tense is smogged.
The past tense of "dwell" is "dwelt" or "dwelled." Both forms are correct and can be used interchangeably.
The past tense is moulded. Note that this is the British and Canadian spelling. The US English spelling is "mold" and "molded".
The past tense spelling of "OK" is "OK'd" or "OKed".
The correct spelling for the past tense of "beat" is "beat."
That is the correct spelling "bought" (the past tense of to buy).
The correct past tense spelling of "label" is "labeled" in American English and "labelled" in British English.
The correct past tense of "initial" is "initialed."
They tripled.