Have you finished your laundry?

I have written two posts on present perfect this week. I wrote them on Monday and Tuesday. You might want to read them first.

http://upgradeenglish.blogspot.com/2009/05/now-that-i-have-had-dinner-i-can-write.html
http://upgradeenglish.blogspot.com/2009/05/yesterday-i-started-series-of-posts-on.html

Yesterday, I mentioned that one reason to use present perfect is to talk about something that happened before but is important now. On Monday night, I was in class at a company. This was part of our conversation:

A: Can you go home after class?
B: Yes, because I've already finished all of my work. In fact, I finished it before lunch.

It was a joke; she didn't really finish before lunch, but she had finished her work.

When the events aren't really important now, don't use present perfect tense.

• ○ (at an accident) Has anyone been injured? (the accident just happened, and you wonder if you need to call an ambulance) <- present perfect
• ○ (telling the story about the accident) I saw an accident today, but fortunately no one was injured. <- past

Sometimes the past events become important now because they directly relate to the current situation or conversation topic.

A: Can you really run from here to Yokohama?
B: Yes.
A: Really? Why?
B: Because I have run marathons several times.

Sometimes this is paired with a past event. The news is contrasted with a past event.

• × I have been injured, but I'm well now. <- the injury isn't important now; being well is important
• ○ I was injured, but I have recovered. I'm well now. <- use present perfect to point out the important news

I haven't done the laundry yet, so I should stop my post here. I don't want to stay up too late tonight. I haven't finished telling you everything I want to say about present perfect, though, so I will be writing about it again tomorrow.