I'm learning English from a TV show and a textbook. I showed some dialogues to a native speaker and she pointed out a sentence. This is the context.

Officer : Have you visited Vietnam within a month?

Dave : No, I haven't.

Officer : Okay. How long are you staying in Vietnam?

Dave : For 12 days. I don't need a visa, right?

Officer : That's correct. You can stay in Vietnam for 15 days without a visa. Do you have a return ticket?

Dave : Yes, here it is.

She said - It should say "within the last month". We would understand it but it would be better to say "have you visited Vietnam within the last month" or "the past month"

I think if she is correct, it's because 'within a month' means 'before a particular period of time has passed from now' so it's not allowed to say with present perfect. Am I correct or are there any other reasons?

A native speaker is a co-host of the show and I heard there are some proofreaders before the book publishes. That's why I am confused and double-checking.

Thank you so much in advance.


You are right that she is correct, but your reason is not quite correct. The meaning of "within a month" is clear from the context but the phrase sounds incomplete; within a month of what? That could refer to a period of a month from a date in the past just as much as to a period starting now. On its own the phrase is either the beginning or end of something. So you could have "within a month of New Year's Day" or, but not in this context "You will have to leave here within a month".

  • Thank you so much, JeremyC. You answer sounds like we need a starting point to say 'within'. So when we say 'within a month' for future, current is a starting point. Also when we say 'within the last month' with present perfect, current is a base time too. – user3547458 Jan 28 '18 at 9:57
  • Yes. "He graduated from college in May 2017. Within a month, he had landed a job with a prestigious investmen bank" (before one month has elapsed). – tenebris2020 Jan 28 '18 at 9:58
  • "Their birth dates are all within a month of yours"—here it goes in both directions. But yes, there always needs to be a starting point. In the show, I assume, the officer is Vietnamese, so even American or English screenwriters will try to reproduce some kind of a broken English. – tenebris2020 Jan 28 '18 at 10:00
  • Oh, placing a starting point in a different sentence in your example is very interesting. I also think the writer of the book traveled Vietnam a lot so she could hear the sentence many times. – user3547458 Jan 28 '18 at 10:21
  • There is a reason "within the next/last thirty days" is used instead of "month." – KarlG Jan 28 '18 at 11:22

Have you visited Vietnam within a month?

within a month implies a future month, but then you used a past participle in the question and in the answer:

No, I haven't.

To fix this mess

If your intention is to ask about a time span in the past, you'll want to change your question to

Have you visited Vietname within the last/past month?

If you intention is to ask about a time span in the future, you'll want to change your question to

Will you visit Vietnam within a month? (meaning "within the next")

  • @user3547458 Great! Feel free to accept this answer by clicking the check mark. – Jonathan Komar Jan 28 '18 at 10:03
  • @JonathanKomar It should be "Present Perfect", not "past participle" (I don't have enough reputation to edit it directly). – tenebris2020 Jan 28 '18 at 10:19

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