The word ‘through’ is primarily used as a preposition, and it does not have a past tense because it is not a verb. Instead, when using ‘through’ in a sentence, it functions to indicate movement from one side to another or to signify completion of a process.
For example, if you want to express that someone moved from one side to another in the past, you would use a verb in the past tense in your sentence, such as ‘went through.’ Here, ‘went’ is the past tense of the verb ‘go,’ while ‘through’ remains unchanged.
So, while ‘through’ itself doesn’t have a past tense, you can describe actions that include it by altering the main verb in the sentence.