I've got a sentence on a learner's site, "This is the watch that I had lost" and now it's puzzling me. What's the rule to use the Past Perfect here? And why should I use specifically this tense?
It's stated, that this sentence is right and well-formed. But if someone replaced "had" by "have": "This is the watch that I have lost", it would be impossible unless the watch is shown on a photo. Is it right?
Why can't I just use the Past Simple here: "This is the watch that I lost" ?