英語三級每日口語(6.7)：Does it serve your purpose?

Does it serve your purpose?
    這對你有用嗎？
    今天的幾個句子是有關(guān)質(zhì)疑的：
    1.Is it very useful like that?
    那樣會很有用嗎？
    2.Be it useful trying that way?
    那樣做有用嗎？
    3.Is there any purpose in waiting?
    等下去有用嗎？