He had traversed a long/long distance.

He had traversed a long/long distance.
What is the difference between them?

‘He had traversed a long distance.’ is the only correct one.

He had traversed long distance.
Why this is wrong? I request for an sensual explanation.

I don’t think you mean ‘sensual’.

In this context ‘distance’ needs an article. It often (but not always) does when it is a noun. Here it means the amount of space between two points.

Beeesneees,

  1. Paul has to drive very long distances as part of his job.
  2. Paul has to drive a very long distances as part of his job.
    Are both sentences correct?

My intention was to make an adjective of “sense”. But I didn’t cheek it by dictionary.
I really didn’t mean “sensual”. I am deeply sorry for such a mistake.

I think you mean ‘sensible explanation’. The article is needed for the singular word ‘distance’ in the same way as you would say: He walked a mile. In the plural there is no need for an article: He walked many miles. ‘A’ simply means ‘one’.

Hope that is sensible!

Yes Alan I meant “sensible”.
I understand your explanation. I am grateful to you for your enchanting explanation.

Beeesneees,
I don’t find answer for my questions.
Could you please help me.

Only the first of your sentences is correct.