Why it is neccessary to use Present Perfect Continuous not Present Perfect in the sentence below?
TB: It sounds like a very busy day.
MR: Oh, that's only part of it. I have had two meetings, one with Union representatives and one with departmental heads. And I HAVE ALSO BEEN WORKING on a proposal for a new marketing strategy.
TB: And it's not two o'clock yet.
If I say "And I HAVE ALSO WORKED" that's a mistake, so why Present Perf. Cont.?

Question

Answer

The present perfect continuous is used the action, started in the past, is still in progress.

Answer

In this example, if MR were to say "I have worked", I'd think the project was completed. But no, there's still more to do.

Answer

MR is describing how he has been spending his day, with the emphasis on how busy he has been and what activities he has been engaged in. The focus is on the activities themselves, and this is why the continuous tense is used. We would understand that the proposal is not yet completed. The reason he mentions the proposal is simply as an explanation about how busy he has been.

Compare it with this conversation.

TB:How's your day been?
MR: Not bad. I've finally done the proposal for the new marketing strategy. That's a relief. I've been working on that for weeks, and I'm glad I've finished it at last.