It can be used to describe:
* Duration: "He slept long and soundly."
* Distance: "We walked long into the night."
* Extent: "The river stretches long and winding."
The adverb form of "long" is the same as the adjective form.
It can be used to describe:
* Duration: "He slept long and soundly."
* Distance: "We walked long into the night."
* Extent: "The river stretches long and winding."
The adverb form of "long" is the same as the adjective form.