I worked hard OR I did work hard ?

Could anybody explain me a difference between following expressions:
I worked hard and I did work hard (or Present Simple: I work hard OR I do work hard)

The versions with the verb "do" imply that you are refuting someone else's statement of the opposite, i.e., that you did/do not work hard. You are saying, "Yes, I do."

OK. But what about a case when such expression is included in monologue? When speaker do not argue with anybody? What does it mean in that case?

It is just a way of putting a stress to it. In present tense you may say: "I do work hard" and it means "I REALLY work hard!". In past tense it will be "I did work hard!"

In Older English, it's just a more poetic form. Shakespeare often uses it, but it still has a connotation of emphasis.

Find an elementary English grammar and you will have the answer, because it is something that you'd learn in first year studies.

May be this is reasonable advice, Chaika, but if you look in Murphy`s grammar (it is not the worstest book) you won`t find the answer. So thank you, Chaika but I don`t think it was worth advising me that. :?

here's an example of how you would use the terms in a conversation:
you: i worked hard
friend: you didn't work hard
you: i DID work hard!

basically, "i worked hard" is how you would express the fact that you put a lot of effort into working.
"i did work hard" would only be used if you were arguing or debating with someone, and you would stress the word "did".


the words "do, did.." work like that in most situations with verbs.
normally, you should just say "i love you" or "i took the garbage out" or "i bought the car" etc.
UNLESS someone tries to say that you are lying. then, you would say: "i DO love you" or "i DID take the trash out!" or i DID buy the car!"

Also, you might say:

"I do work hard, but I can never get my homework in on time" etc., where something you are saying hasn't been refuted, but there is a contrast that could refute if someone else said it.