An adverb is a word that modifies a verb. 'Hard' is not a verb, therefore it can't have an adverb tacked onto it. If you wanted to remove 'hard' from the sentence and make a new one that includes an adverb, and has basically the same meaning, you could do something like this: "The carpenters strenuously worked all day without food or water."
worked
The colours in the painting were vivid. I had a vivid dream last night vivid vivid vivid
No, it is not. It is the adverb form of the adjective vivid (bright, clear).
I have many vivid dreams at night, but not so vivid during the day.
After the sun rose, the sky became a vivid shade of blue.
the colors were so vivid . The photo was very vivid .
i have no idea, LOL
I had a really vivid dream last night and woke up with a woodie.
Laboured, sweated, slaved are some examples.
The sunset painted the sky with vivid shades of pink and orange.
She gave us a vivid description of her trip.
The verb is: are.