Sentence examples for this were from inspiring English sources

"this were" is not a correct usage in written English
The correct form is "this was." "Were" is the plural past tense form of "be," while "was" is the singular past tense form. Incorrect: This were a difficult decision to make. Correct: This was a difficult decision to make. Incorrect: This were the best days of my life. Correct: This was the best day of my life. Example: Incorrect: This were the rules that were set forth by the committee. Correct: This was the set of rules established by the committee.