The difference between "until" and "by"

cheshire

Senior Member
Japanese
Hi, everyone. Which is correct?


1, She won't be back until 5 o'clock.
2, She won't be back by 5 o'clock.




Is the following interpretation correct?

1 - she will be back at 5. 2 - She will be back after 5.
 
  • ryuusaki

    Member
    English & Chinese
    You interpretation is correct.

    PS. 2. She won't be back by 5 o'clock means she won't be back before 5 o'clock. It might sound the same, but I just think that there is a subtle difference between "will be back after 5" and "won't be back before 5".
     

    cuchuflete

    Senior Member
    EEUU-inglés
    1, She won't be back until 5 o'clock. = She will be back at 5, but not before 5.
    2, She won't be back by 5 o'clock. = She will arrive at some unknown time later than 5.



     

    cheshire

    Senior Member
    Japanese
    Thank you very much, everybody!:)
    I don't understand why the sentence 2 doesn't allow for this interpretation: that 2 includes 5 o'clock sharp.
     

    AWordLover

    Senior Member
    USA English
    Thank you very much, everybody!:)

    I don't understand why doesn't the sentence 2 allow for this interpretation: that 2 includes 5 o'clock sharp.​

    HI cheshire,

    Of course sentence 2 includes 5 o'clock sharp. We just don't agree on whether she may return by then. :D

    I think the differing views are clear in the posts.
     

    Forero

    Senior Member
    Hi, everyone. Which is correct?

    1, She won't be back until 5 o'clock.
    2, She won't be back by 5 o'clock.[/I][/I]

    [/INDENT]Is the following interpretation correct?

    1 - she will be back at 5. 2 - She will be back after 5.

    All these sentences are correct. Let me try to explain the meanings:

    1. "She won't be back until five o'clock." This means that before five o'clock she will not be back. It almost says she is planning to be back at five o'clock, but does not make a promise to that effect.

    2. "She won't be back by five o'clock." When "by" is used in a positive statement, it makes a promise ("by" = "at or before"), so this statement is negating a promise, saying in effect that she was planning to be back by five o'clock, but she has had to change her plans. She cannot be back by five o'clock and is relaying this fact through the person making the statement.

    3. "She will be back at five." This means that her expected arrival time is five o'clock. This should imply that, come five o'clock, she will be here, but I have had the disappointment on more than one occasion to learn that someone that "will be back at five" came back sooner and was gone again before five o'clock.

    4. "She will be back after five." This means that her expected arrival time is after five o'clock.
     

    cheshire

    Senior Member
    Japanese
    Thanks, I understood deeper on this matter!
    1, She won't be back until 5 o'clock.
    2, She won't be back by 5 o'clock.
    I now realized that these two sentences are different in structure.
    3. She won't be back not until 5 o'clock.
    4. It isn't likely that she is back by 5 o'clock.
    In declarative sentences, "until" doesn't usually include the end of time. Hence, its negative "not until" includes the end of time. (includes 5 o'clock).

    "by 5 o'clock" in "She is back by 5 o'clock." may include 5 o'clock. In Sentence 4, even though the setence is a negative, that doesn't affect "by 5 o'clock" but the verb "is."
     

    Forero

    Senior Member
    Hi, cheshire.

    These sentences apparently set lots of wheels turning in my mind when I am faced with interpreting them. But the wheels in your mind seem to be meshed quite differently than mine. :)

    In particular, your versions of 3 and 4 are not grammatical, and I don't understand what you are saying about them. If you want, I'll explain where I have trouble with them, but I'll go ahead and get right into more detail on what "until" and "by" a specified time mean to me.

    "Until" a specified time refers to a time interval ending with that time. "She will be back until five o'clock" means that she is back or will be back and will stay here till five o'clock and at or after five o'clock, perhaps, she will leave again. "She won't be back until five o'clock" means that she is away or will be away and will stay away till five o'clock and then at or after five o'clock, perhaps, she will come back.

    "By" a specified time refers not to an interval but to a time of completion no later than that time. "She will be back by five o'clock" means that after five o'clock we will not be able to say "She is not back yet." Contrariwise, "She won't be back by five o'clock" means that we shall indeed be able to say "She is not back yet" until some time after five o'clock. Then, who knows?
     

    cheshire

    Senior Member
    Japanese
    Thanks!
    What about the structure? Is my structural perception in #8 wrong?

    Could you tell me which part are wrong grammatically in 3 and 4?
    Thank you.
     

    Forero

    Senior Member
    I'll have to come back to this after a good night's sleep. It's 2am where I live. But here are some clues:

    3. She won't be back not until 5 o'clock. :cross: [Double "not", with one misplaced]

    Did you mean "She won't be back. Not until five o'clock"?

    4. It isn't likely that she is back by 5 o'clock. :cross: [Present indicative after "it isn't likely that"; logic problem with By 5 o'clock used with simple present tense]

    Did you mean "It isn't likely that she will be back by 5 o'clock."?
     

    tomandjerryfan

    Senior Member
    English (Canada)
    I don't think I would say She won't be back by five o'clock.
    I think I would say She won't be back until after five.

    I agree. Your version sounds more natural, but I sense a subtle difference in meaning here. "By" includes at five o'clock; "until after" does not - it only implies any time after five.
     

    Teafrog

    Senior Member
    UK English
    All these sentences are correct. Let me try to explain the meanings:

    1. "She won't be back until five o'clock." This means that before five o'clock she will not be back. It almost says she is planning to be back at five o'clock, but does not make a promise to that effect.

    2. "She won't be back by five o'clock." When "by" is used in a positive statement, it makes a promise ("by" = "at or before"), so this statement is negating a promise, saying in effect that she was planning to be back by five o'clock, but she has had to change her plans. She cannot be back by five o'clock and is relaying this fact through the person making the statement.

    3. "She will be back at five." This means that her expected arrival time is five o'clock. This should imply that, come five o'clock, she will be here, but I have had the disappointment on more than one occasion to learn that someone that "will be back at five" came back sooner and was gone again before five o'clock.

    4. "She will be back after five." This means that her expected arrival time is after five o'clock.

    I think that's very well explained. Well done Forero. :thumbsup:
     

    cheshire

    Senior Member
    Japanese
    Thank you very much!:)
    HI cheshire,

    Of course sentence 2 includes 5 o'clock sharp. We just don't agree on whether she may return by then. :D

    I think the differing views are clear in the posts.
    I'm very sorry, which do you mean?

    (a) She won't be back, even at 5 o'clock.
    (b) She won't be back, but might be back at 5 o'clock.

    I'm sorry, my question was vague and ambiguous.
     

    tomandjerryfan

    Senior Member
    English (Canada)
    "She wont be back by five o'clock" means she won't be back before five o'clock or at five o'clock. She might be back some time after five o'clock though.
     
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