If you require some information you can say: (来源：英语麦当劳www.EnglishCN.com)

    Could you tell me if/when/how much/why...?

    I wonder if you could tell me...?

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    I'd like to know...

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    I'd like some information about... (来源：英语交友 http://friends.englishcn.com)

    If someone asks you for information you can reply:

    As far as i know...

    Well,(in confidence,) i can tell you that... (来源：英语美食指南 http://food.englishcn.com)

    I'm afraid i don't know...

    I've no idea,I'm afraid... (来源：英语博客 http://space.englishcn.com)

    I don't have that information available just now,can i call you back?

    I'm not sure,I'll have to find out,Can i let you know tomorrow?

    I'm afraid i can't tell you that,it's confidentail. (来源：EnglishCN英语问答中心[e问e答])