How do you say something like that?
“There’s a thing for which I don’t know what it is” “There’s a thing where I don’t know what it is” “There’s a thing that I don’t know what is”
or (the one which I hear people say a lot but sounds awkward:) “There’s a thing that/which I don’t know what it is”?
To be honest they all sound awkward to me to varying degrees
Best sounding recommendation probably depends on context and ‘the thing’:
There’s a concept I don’t understand.
There is something in the box I don’t recognize.
There is a feature of the coffee machine I haven’t figured out yet.
There’s a Greek word in the original text that I don’t know.
To clarify - I think your proposed grammar is valid but the phrasing is uncommon. It’s not a phrase I would expect to hear. Though I would understand the gist of what you’re expressing.
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