Difference between Future tense and Future perfect tense

Discussion in 'English Only' started by redgiant, Oct 21, 2008.

  1. redgiant Senior Member

    Cantonese, Hong Kong
    According to the some books, future perfect means the action will finish at a point in the future.But Problems arise once making a tense comparison. I get confuesd when comparing it with future tense in the following sentence:

    The bus will have left before we reach the station.
    The bus will leave before we reach the station.

    The first sentence means the bus's departure will already finish before we arrive at the station, so we can't see the bus at the station. But I can't figure out the difference of future tense from future perfect tense here
  2. kitenok Senior Member

    This is true; the future perfect can only mean that the action will have been completed. Simple future can also meant that the action will have been completed, but it can also mean other things in other contexts. In the examples you give, the meanings of the tenses overlap completely (I think ;)). This happens frequently when we have a sequence of actions clearly indicated with a time clause like "before XYZ."

    If we take a time clause that doesn't necessarily indicate the sequence of actions (say one with "at" rather than "before" or "by the time that"), then we see that there are instances when future perfect and simple future can mean different things:

    At 6 o'clock I will leave. = The action of leaving will begin at 6:00.
    At 6 o'clock I will have left. = The action of leaving will be complete by 6:00.
  3. Outsider Senior Member

    Portuguese (Portugal)
    The meanings of the two do overlap sometimes, especially when the verb is in a dependent clause, like in your example.

    However, the future perfect emphasizes that the action will be finished before some future time or event. So, it's used mostly when relating two events.
  4. redgiant Senior Member

    Cantonese, Hong Kong
    Great!:D Thanks for your helps~

    One more question

    If I want to say that in the next hour, he will play computer games and finish it. Then he will prepare your arrival, can I say:

    He will have played the computer games before you come?
    Last edited: Oct 21, 2008
  5. kitenok Senior Member

    Well, grammatically speaking, yes, you can say that. To my ear it is strange to use future perfect here, if only because it is a strange thing to emphasize the act of finishing playing computer games before a certain point in time. "I will have cleaned the house before you come" sounds like a more natural context but, like your first pair of sentences, the meaning overlaps with simple future "I will clean the house before you come."

    Here you will find links to several previous threads on future perfect tense, which will give you many more examples and explanations. I found this by typing "future perfect" into the dictionary look-up search at the top of the page. This web site also has some very good explanations and exercises on English verb tenses. Good luck! :)
  6. JamesM

    JamesM à la Mod

    Often the future perfect is in relation to a point in time. Although this sentence is possible, it sounds more natural when it refers to a specific point in time:

    By the time you get here he will have finished playing the computer games.

    (Specific point in time) (completed action)

    The same is true for the bus and the station for me:

    The bus will have left by the time we reach the station.

    (Completed action) (specific point in time)
  7. Aardvark01

    Aardvark01 Senior Member

    Midlands, England
    British English (Midlands)
    The term 'perfect' in 'future perfect' means 'complete'. I have found it useful to illustrate graphically thus:

    The bus will have left before we reach the station. <----¬

    The bus will leave before we reach the station.
    Now _____________---->

    The red arrow ---> indicates the point at which we reach the station and the direction from which we are speaking about it.

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