Does using "did" to form the past tense make a difference? [duplicate]

The two sentences here both indicate that, at some point in the past, I performed some work:

• I did work

• I worked

What is the difference between these two sentences? Does constructing one with did and the other with a simple past change the meaning?

Solution 1:

There are three common usages for the auxiliary verb do:

1. Emphatic do - strongly stressed, often contradicting something in context
   Q: Why didn't you tell her? A: I did tell her.

2. Active do - pro-verb substituting for active (non-stative) verb
   What I want to do is buy that house now ~ *What I want to do is own that house now

3. Do-Support do - dummy verb, no meaning, necessary in questions, negatives, etc.

So, it depends on the construction. A simple sentence like I did work has to be Emphatic, because Active do is a pro-verb and pro-verbs only occur in certain constructions, which this is not; and Do-Support do never occurs in this construction either -- it's a marker of many constructions, but not of this one.

Auxiliary verbs are part of the syntax, and may or may not mean anything. It's the constructions they're in that are important; English syntax is about constructions, not words.

Solution 2:

It is perfectly grammatical indeed, but this way of sentence construction is used to emphasize that you really performed the action you are talking about. Thus

I did work (and I did get results)

means that you really worked (and that you really got results).

More information on emphasis you can find here:

http://www.michellehenry.fr/emphasize.htm

and here:

http://www.bbc.co.uk/worldservice/learningenglish/grammar/ask_about_english/071112/