Well, no, it’s quite logical, but it does have different uses. We often use present perfect for talking about something which happened in the past which is important now.

My Chinese teacher has given me some homework. (= I have the homework to do now.)
I’ve forgotten. (= I can’t remember now.)
She’s broken her leg. (= Her leg is still broken now.)

We also use present perfect with just for talking about a recent action.

Oliver’s just made a cake.

Yes, that could be the reason. But with just for recent actions we usually use present perfect, anyway.

You could, but then the focus would be more on the action rather than the result. Maybe you are explaining why the kitchen is in a mess. We use the present perfect simple more when there is a result in the present (like the cake) and the present perfect continuous more when the action is important.

Exactly. Because we’re more interested in the action than the result.

No, not at all. We also use it for life experiences which happened at any time in the past. The person’s life, which continues in the present, is the link to the present.

She’s won an award.
Sophie has been to Berlin before.

Exactly, we don’t know when and it isn’t important. If you wanted to say when, you would have to use the past simple: ‘Sophie went to Berlin ten years ago.’

We also use the present perfect for actions or states that are unfinished.

Your mum’s been writing her blog for years now, hasn’t she?

She is still writing the blog now, so the action isn’t complete.

No. We usually use the present perfect continuous for talking about the length of time something goes on for, with phrases like for years, for a long time, etc.

We use already to talk about something which has been done, and usually this is surprising to the speaker.

Wow, that was quick! You’ve finished your homework already.

Yet is mainly used in questions and negatives to talk about something which hasn’t happened, but which you thought would happen in the past and you expect to happen in the future.

I haven’t had time yet.
Have you seen her new blog yet?

We use still to talk about something which is going on longer than you expect.

They’ve been doing things with that computer for ages, but they still haven’t fixed it.

Oh, sorry, you can’t say ‘I’ve been understanding’. Do you remember when we looked at the present continuous? There are certain verbs, called state verbs, which we don’t usually use in the continuous form – verbs for talking about emotions, thinking, existing, appearing, possession and the senses.

That’s right, they’re in the Grammar Snack on the present continuous.

For a few minutes!

Excellent – you used present perfect continuous with a length of time and present perfect simple with a result!