Hello Dudumuzik,

Welcome to the forums.

A transitive verb requires a direct object. You picked a hard one - grammatically, we don't say "I knocked the door." There is an expression "knock wood," but it's an idiom.

Was your question specifically about the verb "to knock" or about transitive verbs in general?

Dudumuzik wrote:

I want to know more about transitive verb and intransitive one.it is so  prevalent that there are so many verbs which have both two forms. such as  POKE                     He was poking at the ashes.                     Don't poke into my private affairs.                    He poked about in a second-hand bookstore. I think they all have objects(ash, affairs,bookstore ), why  use the intransitive form?                     He poked me in the ribs with his elbow.                    He poked a stake into the earth.                     She was on her knees, poking the fire.                     He poked a hole in the paper But i dont think" hole" is an object. Could you please elaborate that?thank you very very much

Transitive (with direct object)  I'm not sure I would call 'hole' a direct object, but I don't know what else to call it.  I'll let the more gifted teachers clear this one up.