if I knew / if I know

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pickyx

Senior Member
Chinese
Which sentence is correct?




1.If I knew his number, I would tell you. (why knew not know?)
2. If I know his number, I will tell you.


Why?

Please help me out!
 
  • owlman5

    Senior Member
    English-US
    The two sentences are different types of conditional statements.

    1.If I knew his number, I would tell you. (why knew not know?)
    This sentence is normal if you are sure that you do not know his number: If I knew his number, I would tell you. (But I don't know his number, so I can't tell you.)

    If I know his number, I will tell you. :confused: This sentence is normal if you are not sure whether you know his number. If you do know his number, you will tell me. Speakers know whether they know a number or not, so this sentence is unlikely.


    Here's a better example: If I still have his number in my address book, I will give it to you. :thumbsup:

    You might be interested in this information about different conditional sentences from the English Page: conditionals If you study that material carefully, you'll have a good understanding of how to use the different types of conditionals.
     
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    pickyx

    Senior Member
    Chinese
    Thank you very much owlman5! Your answer is very helpful, especially the link of English Page.
    About " If I knew his number, I would tell you. " , I still don't get why it is knew (past tense).
    Please help me! tks!
     
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    owlman5

    Senior Member
    English-US
    You're welcome. I'm glad the answer was helpful.

    "Knew" in that conditional statement is not the simple past. It is the past subjunctive of the verb "know". People sometimes use the past subjunctive when they are talking about things that aren't real or true: If I were a rich man, I would buy an airplane. ("Were" is the past subjunctive.) I am not a rich man, but if I were one, I would buy an airplane.

    You can find more information about the subjunctive by searching for that term (English subjunctive) with a search engine.
     
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    nightdragon

    Senior Member
    Chinese-China
    Last edited:

    pickyx

    Senior Member
    Chinese
    owlman5, I am very grateful, I think your explain almost gets me what I wanted.
    What confuses me is the past subjunctive, which I first heard. I just don't get why it have to be knew, when it comes to Present Unreal Conditional.

    Thank you again!
     

    pickyx

    Senior Member
    Chinese
    "If I know his number, I will tell you. :confused: This sentence is normal if you are not sure whether you know his number. "

    Just to be clear, is normal not abnormal?

    Also, owlman5, would you please clarify me that the simple past
    knew is different from the knew of If I knew his number?

    Thank you!


     

    owlman5

    Senior Member
    English-US
    Just to be clear, is normal not abnormal?
    I'm sorry if I was unclear earlier. I think it is abnormal because speakers are ordinarily aware if they know something or not. The grammar would be normal if you really didn't know if you knew the number, but that seems very unlikely to me.

    Also, owlman5, would you please clarify me that the simple past knew is different from the knew of If I knew his number?
    I'm not sure I can do much to help you other than to direct you to a discussion of the past subjunctive *in English. I think you are confusing the past subjunctive with the simple past. That's not surprising because the spelling and pronunciation of the verbs used to convey these meanings is identical for most verbs:

    "bless" (the verb)

    simple past:
    I, he, she, it, we, you, they blessed

    past subjunctive
    I, he, she, it, we, you, they blessed

    "Blessed" in these examples is identical in appearance and sound. However, "blessed" has a different function in the past subjunctive than it does in the simple past. The past subjunctive is used to represent hypothetical or unreal statements about something. The simple past is used to report some event that took place in the past.

    *Grammaring. com: past subjunctive. You can find many similar pages about the past subjunctive by searching for that term on the internet.
     
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    pickyx

    Senior Member
    Chinese
    Dear owlman5, you don't know how helpful and important your explanations means to me. I am very grateful. Thank you!

    Still I have another question about the sentence you used "I'm glad the answer was helpful." why was helpful, not is helpful?

     

    owlman5

    Senior Member
    English-US
    You are very welcome. I used "was helpful" because I was referring to a moment in the past when you found that answer helpful.
     
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