The Rivers and the sea（在线收听）

    Once upon a time the rivers combined against the sea，and con-verging into a whole，accused her，“Why is it that when we rivers pour our water into you so fresh and Sweet，you straightway render it salty and unpalatable？”The sea，observing the temper in which they came，merely answered coldly，“If you do not wish to become salty，please keep away from me altogether．”
    Those Who are most benefited are often the first to complain．Exercises：
    回答下列问题：
    ① Whom did the rivers combine against？
    ② Why did the rivers accuse the sea？
    ③ What did the sea say when she heard what the rivers said？
    ④ What can we learn from this fable？