Thanks for your detailed explanation. I understood :)

This is grammatically correct, but it sounds weird alone. We typically use this tense to describe a past tense situation when a past tense event occurred. So, if that's all that you did, you "left" it on the table. If something happened after you left the yogurt on the table, you would use "left." The way you have it is right if something happened as you were in the process of "leaving" the yogurt on the table. It would mean that whatever you were doing (in this case, you were leaving the yogurt) occurred before or during another event in past tense. Examples: I left the yogurt on the table. I left the yogurt on the table, then the phone rang. I was leaving the yogurt on the table when the phone rang.