I think that that that that that boy used is wrong. sembra naturale?

@prominencial As @cmertb wrote: "Wow!" I hope that their question was either (1) is it grammatical, not _natural_ (a loaded concept), or (2) about punctuation, or (3) a translation-into-Japanese (if possible -- probably requiring a rephrase for the sense). Sometimes, similar sentences with five "that"s in a row appear in disucssions of what's called "recursion," which is probably a universal feature of all languages. ("Probably" hides some details, obviously. :-) ) It's easy to keep adding two-to-four "that"s per level of recusrion. For example, do you think that that "that that 'that' that that" that that exam question asked you about was fair? And once you've let that (so to speak -- sorry) sink in, what about << Was the use of that "that that 'that that "that" that that' that that" that Misha's example used natural? >>? Overall, my own take on such issues is that although they are impossible to fault syntactically, and while recursion is most likely a universal feature, nevertheless such examples demonstrate that there is a limit on how many levels of recursion a person can easily retain in memory. There are examples with "had" and "had had" and there are examples with sentences like "The mouse the cat the dog chased killed ate the cheese" or "The mouse the cat the dog the maid kicked killed ate the cheese" or "The mouse the cat the dog the maid the butler liked kicked killed ate the cheese." They're all fun and games, but they belong more to the realm of linguistic theory than to the realm of what most people say -- up to a certain number of levels, depending on the person and the form of recursion.