What is past tense of the word put?

In this case, "put" serves as both the past and the present tense. Some people think "put" sounds like slang and they prefer that you use "placed," but actually, "put" is a perfectly valid word. I put the book on the desk (present tense). I put the book on the desk (past tense)-- to tell the difference, all you have to do is include a word that explains when the action occurred. For example, Yesterday, I put the book on the desk.