I think, in formal usage, you will find that American and British are basically identical. We each use both of those constructions in the appropriate situation. Obviously, there is a semantic difference between these two constructions and neither dialect exclusively uses one or the other.
I am not certain, but I think what you are referring to is the fact that American English speakers can sometimes use simple past in places where one normally uses present perfect. So, as a US English speaker, I would correctly say:
(1) I've never gone to a tennis match before, but I am going to one today.
But, sometimes I say:
(2) I never went to a tennis match before, but I am going to one today.
I would not say that this second example is standard US English — in any formal situation I would use the present perfect. But, I suspect it is common in speech and I do it quite often.
This could be the very beginning of a semantic shift in the present perfect construction in English. Perhaps (2) will be preferred in several hundred years. (Such things are not unheard of; German now uses the present perfect form to indicate simple past in speech.)
If a non-native speaker asked me about this, I would never recommend to use the construction in (2), because (1) is right in every situation and never sounds strange or formal.
when you say “I wrote my article yesterday,” does this imply that at this moment you have a finished article or not?
Yes, you finished it. Otherwise, as you say, you would say something like "I started to write my article yesterday". In that case, 'started to write' has finished even if the article hasn't.
What about present perfect? Does it imply completeness?
No, it doesn't. Present Perfect is 'until now' or 'relevant now'. It says nothing about what happens after now, though context might. For example:
"I have worked in that factory" implies (by using 'that') that you no longer work there. Maybe somebody is asking you what is inside, and you have relevant knowledge because you have worked inside the building.
"I have worked in this factory for ten years", but this is your last day. You have worked here until now.
"I have worked in this factory for ten years", so you know where the toilets are and don't need telling. Unless you get sacked you will continue to work here.
do I have to use past continuous to emphasize the incompleteness of action?
If the action is incomplete, you use present continuous. Past continuous is for a finished action.
In your example “I was watching this film”, the action - the watching - is complete. You are not watching it any more. Whether you completed the film or not doesn't really come into it, as the film is not the action.
Best Answer
Both indicate an action that occurred (and was completed) in the past. The
In principle the perfect tense is used to indicate that an action or circumstance occurred earlier than the present time (or other time under consideration) and often focuses attention on the resulting state rather than on the occurrence itself. In your example
the emphasis is on the fact that you can now use the account because you have already created it in the past.
I've tried to help you... seems to wait for something more that is happening today.
It is different than I tried to help you (...?) There is no expectation that it be tied to the present.