I'm not an English teacher by profession, though I'm helping out some German friends with their English.

They usually ask for a more grammatical explanation The following sentence is clearly incorrect, but how do I explain it in grammatical terms?

* I worked really hardly and we got the contract.

I think it's got something to do with not following one adverb ending in -ly with another - but then again, we can say 'really,really...'

I would be very grateful for any help to clarify this please
Here, the problem is not grammar, but meaning.
"Hardly" very rarely means today "in a hard way," but most frequently "barely, in a minimal way"
You need to use "hard" instead, which does work as an adverb too.
Oops! You posted twice. (Thanks for the link in the other thread, Marius.)
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