You are asking for a precision which doesn't exist. When until is followed by a period of time rather than a point of time, it is not specific whether or not the "until" lasts into, or even to the end of, that period.

@Colin Fine -- Your comment would make a good answer.

@Colin Fine @ Jasper No, I think you're WRONG. There IS a precision which exist. For example, "Tom will be away until Monday." means "so, he'll be back ON Monday." How can you native speakers make such an incorrect answer? I don't understand.

So, @niue, you aren't one of "you native speakers", but you're presuming to tell me how my language works? Why ask the question if you're going to argue with me when I answer? I agree that "Tom will be away until Monday" usually means that he will be back on Monday, but it doesn't reliably mean it. One of the things that goes into the interpretation is real-world knowledge about working weeks; so "away until Monday " probably does mean they'll be back on Monday, because people tend to take whole weeks for holiday. But what about "away until Friday"?

@niue, if you think the answer is so precise, what about "until 1960", then? "1960" is obviously not one instant in time. Do you think "He practiced until 1960" means that he stopped on exactly 11:59 PM, December 31, 1959? Colin Fine is quite right; there is some ambiguity in the sentence.

@P.E.Dant Do you know any dictionary that tells the difference? Please let me know. I've referred to LAAD, OALD, LDCE, Practical English Usage by Swan, English Grammar in Use, Collin Cobuild English Usage, etc. (I'm not "shouting". I'm just emphasizing my point.)

@niue: you asked a question on the English Language Learners group about the English language. I responded (in a comment rather than an answer, because I don't believe that the question you posed has an answer). You proceeded first to tell me that I was wrong, and then that you didn't want an answer about the English language, but about some imaginary version of English that you made up. Languages (real world languages) are often complicated and ambiguous. Questions about something that might be English but isn't aren't on topic in this forum.

(I just want simple answers. That's all.) Every learner I have ever taught has said or thought that line, at one time or another. Language is not math(s). The more you know, the more you realise how much there is to master. Advanced English rarely has "simple answers", and if someone proposes simple answers, they're not doing their job properly. Simple answers have a role and a function at Beginners and Pre-Intermediate levels, thereafter it gets messier!

@Mari-LouA Thanks for your explanation about "simple answers in the English language". I understand what you mean, and I really hope to know the intricacies of the English language, but, as a non-native learner, I want to learn the basic rules or usages FIRST. After understanding the basic common usages, I think I can accept the real-world usages. Thanks, anyway!

The examples were identical, so I deleted one set, the original question (which is correct?) has now been expanded. The CAPS replaced with lowercase letters in bold or in italics. I left one phrase in capital letters for emphasis. Too many block capitals in a text looks like someone is shouting.

The question as it stands seems fine, and you have explained the purpose of the multiple choice "test", but if you dislike my edit you can rollback or fix it further. But, what will you do if native speakers respond: "It depends"?

"I would really like to know the source of this revision task (It looks like revision to me), is it a book, or was it taken from a website?" – Mari-Lou A / @Mari-LouA They're mixed. Some of the questions and choices are taken from English Grammar in Use and a web site, but most of the choices are made by me.

@Mari-LouA "The question as it stands seems fine, and you have explained the purpose of the multiple choice "test", but if you dislike my edit you can rollback or fix it further. But, what will you do if native speakers respond: "It depends"?" --- I like your edit and thanks for that! ^^ If native speakers respond "It depends", ......... I'll commit suicide.

Don't shoot yourself, but it almost always depends. As for your precision statement: "Tom will be away until Monday" means "he'll be back ON Monday." That may be true – but what time on Monday? @Colin was right, there is almost always some kind of inevitable ambiguity.

@J.R. Thanks, J.R. OK, then would you please answer the following question? I agree with you that we don't know at exactly what time Tom will be back on Monday, but, at least, we surely know that Tom will be back on Monday, NOT Tuesday. So, there IS a kind of clearness on Tom's schedule. On this point, we don't have any ambiguity. What do you think?

What do I think? I think you should re-read @Colin's initial comment – carefully, this time – and then apologize for quibbling with him about it.

@J.R. Besides, usually, in everyday English, you don't have to know such an exact time when you're talking about someone's return schedule. You just want to know whether he or she returns on Monday or Tuesday. Thus, this is the reason why we don't have any big problem although there IS a "what time" ambiguity in this kind of case. (I'm wondering what you think about my opinion.)

I already gave you my opinion. Read it again. Carefully. The initial comment was spot-on.

@J.R. I don't think you understand my question. Let me rewrite my question: Sometimes, do you accept "Tom will be away until Monday." as "Tom will be back on Tuesday"? Yes, or no?

Do you still find a flaw in the initial comment? Yes or no?

This:

You are asking for a precision which doesn't exist. When until is followed by a period of time rather than a point of time, it is not specific whether or not the "until" lasts into, or even to the end of, that period.

That was the first comment left on your question, and you argued about it (rather rudely, I might add).

All I want to know is if you still disagree with that comment, or if you now understand what the person was saying.

OK. First of all, let me apologize for my attitude.

But, I don't think you understand what I'm insisting.

You say there IS some ambiguity when 'until' is followed by a period of time, and, again, I ABSOLUTELY AGREE WITH YOU ABOUT THAT!

You use capital letters like that one more time, and you'll find yourself in the penalty box for a week.

Do not yell.

netiquette.wikia.com/wiki/Rule_number_2_-_Do_not_use_all_caps

(If you want to emphasize something, however, it is acceptable to enclose text with a pair of double asterisks to make bold print.)

(Or single asterisks to make italics.)

(OK. I'll do not use capital letters. But, do you understand what I'm saying?) When I am talking about "Tom will be away until Monday.", I don't think 'Monday' as "a period of time". It's just a "point of time". (For example, "When is your birthday? This Monday? Tuesday?") Therefore, there's no ambiguity problem even if we use Colin's theory. (And again, I absolutely agree with Colin on his theory.)

So, I'd appreceate it if you answer my former question: "Sometimes, do you accept "Tom will be away until Monday." as "Tom will be back on Tuesday"?

Sure.

I agree with you.

"Away until Monday" usually means he'll return on Monday.

What does that have to do with your question, though, or the conversation above here?

Anyway, there are still ambiguities. If I say, "This coupon expires on Monday," and I try to use it on Monday, will the merchant accept it?

Maybe you can give me an example where there isn't an ambiguity, but that doesn't mean there never is one.

I might also say, "This coupon is only good until Monday."

I understand what you mean. In that "coupon" case, I think 'Monday' is used as a period of time, not a point of time, considering the context. That's the reason why there is an ambiguity in your example.

If the coupon is only good until Monday, when is the last day I can use it? Sunday? Or Monday?

Now that we have all that established, I'm ready for you to try and explain what your question is.

Simply based on my 'Korean culture" thinking, "This coupon is only good until Monday." means "You can use this coupon on Monday."

(BTW, greetings and salutations, Mari-Lou)

I would probably guess the same way, but I wouldn't argue that it's unambiguous.

Then again, most prepositions are somewhat ambiguous by nature.

Simply based on my 'Korean culture" thinking, "This coupon expires on Monday" also means "You can use this coupon on Monday."

Is there another question you wanted to ask about?

Yes. Let me ask you final question. As you wrote, you native speakers usually accept "Tom will be away until Monday." means "Tom will be back on Monday." Right?

That's what I wrote, if that's what you're asking.

And... usally.. "This office will be closed until Monday." as "The office will reopen on Monday." Right?

Sounds reasonable to me.

And.. as you wrote, the following questions have both answers, A and B depending on each situation, right?

@niue Are you simply asking me your question all over again?