Bonjour, grafas,
I'll explain in English, hope you'll understand. The difference between the simple past and the present perfect is in the tense and time. Simple past is used when there is a clear indication of a past time,
a specific point of time, for eg.
Yesterday I saw Mary.
Last night I saw a movie.
Present perfect is used when the emphasis is on the present time, on experience, often used with prepositions like "for", "ever","before", and time phrase like "an hour", "a day", "two weeks" etc which indicate
a period of time, for eg.
I have lived in France
for 10 years.
Have you
ever tried skiing before?
In the passage you gave, though there are no clear indications of past time, the sentences without the " " quotation marks use past tense, because they are telling a story, and a story always happened in the past. For the dialogues with " ", they happen in real time, just like I'm speaking to you. They can be in any tense, past, present or future. But in the story they are about the things that have just happened but used in the present tense, without words indicating a past time like yesterday or two hours ago, so they are in present perfect.
She asked "Charles, darling, have you ever used that sort of key?"
"I (never+do) have never done any housework in my whole life ..this is dreadful !"
Here the meaning suggests the using of present perfect, about experience.
"This house has not been lived in
for years!"
The phrase "for years" is a clear indication of perfect tense, for a period of time, and since the speaker is speaking it in real time, naturally in present perfect tense.
"has been" is the present perfect tense of "be", in passive voice. The present tense is "is lived".
In short:
Simple past: Yesterday, last night, two years ago
Present perfect: today, now, have, ever, never, for a period of time, for two years
The past tense is used for things that happened in the past, with no indication of continuing. The present perfect tense is something that happened in a past time but may continue in the future, for e.g.
I studied English 3 years ago. (My study has ended)
I have studied English for 3 years. (But I will continue my study for a few more years)
Hope you'll understand.
