Has/Has been?

(X) The problem has fixed -- This is not a possible sentence.
The problem has been fixed. -- This is OK.

The second one doesn't indicate the time of the action, right?-- Neither indicates time of action.
So, would that be better to use the first one to mean that "It is fixed, no one is working on it anymore" ? --No, the first one is not possible, but

The same way, can not we say " The train has left" ? but "The train is left"?!

In my text book the first one only being used

No, you cannot say 'the train is left'. Each verb has its own level of capability of becoming an adjective. 'Finished' makes a more generally acceptable adjective than 'left'. Compare 'the finished problem' with 'the left train'.

Ty MM
So are these two mean the same?
1. He is gone
2. He has gone

I am sorry I am quite confused with use of

Yes, they are two ways to say the same thing. The only difference we can make is that #2 tells us it happened recently and/or it is somehow related to something else now.

Thanks MM.

So in that case, which of the following would be a correct way of telling?

Suppose, 3 people are in a place talking about something....1st one tell to the 2nd one to close the door after the 3rd one leaves(left?) the place in a direct speech.

Close the door after he is gone
Close the door after he has gone
Close the door after he went

Best,

@Mister Micawber:

Is it the same with:
I have finished / I'm finished ? Or is there a difference in meaning?

And to 'he is gone' and 'he has gone'. What's the difference between 'he is gone' and 'he went'?
Thanks

These are both OK:

Close the door after he is gone.
Close the door after he has gone.

Is it the same with: I have finished / I'm finished ?-- Yes.
And to 'he is gone' and 'he has gone'. What's the difference between 'he is gone' and 'he went'?-- ''He went' is not possible in that sentence.