The Raven（在线收听）

    A raven observed that an eagle brooded thirty days over her eggs．“Doubtless，”said she，“that is the reason why the eaglets are so sharp-sighted and strong．Good！I'll try the same method．”
    Since that period she has always brooded thirty days over hereggs；but，hitherto，has only succeeded in hatching miserable ravens．Exercises：
    回答下列问题：
    ①How long would the eagle brood over her eggs？
    ②Why did the raven want to do the same？
    ③What did she get at last？