Modal verbs as references to the future perfect

Question

1. By the time you get home, I must/may/might/should have cleaned the house. (Modal verbs used as references to the future perfect)

2.I must/may/should have cleaned the house by Friday.

3. I must/may/should have cleaned the house by next Friday.

By googling, I've leaned that, when "modal verbs" are used as references to the future perfect, only #1 is grammatically correct and makes sense, although unusual, but I'm not really sure why #2 and #3 are not able to describe the future perfect, though I have a seemingly-logical guess at why #2 and #3 are. wrong.

Q1) I wonder whether the reason #2 and #3 are not able to describe the futuer perfect is because even though there are words "Friday" and "Next Friday", they're not contextually enough to make #2 and #3 describe the future perfect? I think that because context is not enough, #2 and #3 still describes the past perfect without more context.

Q2) If everyone clearly knows which Friday the speaker refers to, like if the speaker in front of people is referring to the Friday on the calendar with his finger that will come and saying "#2 or #3", can "#2 or #3" be grammatical, natural and referring to the future perfect?

(In this scenario, the Friday the speaker is referring to with his finger isn't over. The Friday will come)

There is evidence that my guess could be correct in this link "https://ell.stackexchange.com/questions/43312/should-as-future-perfect-modal"

Here, as for sentences A and B, according to context, it seems to be grammatically valid to use "should have done" as a future perfect reference because "then" is obviously referring to the future according to context.

A.The next interview may be more productive if you make it clear what work or thinking the student should have completed by then.

B. Perhaps we'll learn more from the experiments next week. You should have started your tests by then as well. "

I'd like to know exactly and please answer my two questions one by one.

Thank you very much for your help.

AlpheccaStars · Accepted Answer

I do not understand your question. The future perfect tense allows only one modal, that that is "will."

By the time you arrive, he will have eaten all the cookies. (Refers to an action that is completed before a time in the future.)

Your examples all seem to be the modal perfect, where other modal verbs are used.

He has eaten all the cookies. (present perfect)

Modal perfect examples:
He may have eaten all the cookies.
He should have eaten all the cookies.
He might have eaten all the cookies.
He could have eaten all the cookies.
He must have eaten all the cookies.

Not all combinations of time frame (past, present, future) make sense.

For example:

Must works with past and present, but not the future. Must, like will, is definitive and one cannot be definitive about the future, only the past.

He must have eaten all the cookies yesterday afternoon. The tin was empty last night.

This is nonsense:

He must have eaten all the cookies by tomorrow.

How can you possibly know what the state of the tin will certainly be tomorrow?

The combinations of modal forms with past, present and future time references are very irregular. Each modal needs to be studied separately.

This site has some very detailed information, which is mostly trustworthy. I did see one mistake on the page for "could.")

https://www.englishpage.com/modals/must.html

BillJ · Answer

You ask a great many questions, some of which are long and involved.

Please remember that we are volunteers here, not paid employees, so it would be helpful if you kept your questions as short as possible. There are other learners expecting answers too.

Further, it is not helpful to quote answers you have seen on another website. The examples you provide are not always felicitous or natural, so opinions about them may vary.

Thank you.

Modal verbs as references to the future perfect

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