根据课文内容，理解下列句子。   
1．道德只是个简单的是与非的问题，实践起来却很难。   
    (I)“道德”在文中可以理解为                                                                                                     。     
    (2)既然“道德只是个简单的是与非的问题”，为什么“实践起来却很难”呢？
                                                                                                                                                       。
2．父亲的教导让我一生受用不尽——通往广场的路不止一条！     
    (1)“受用不尽”的意思是                                          。“父亲的教导让我一生受用不尽”这说明了                                                                                                                                                   。     
    (2)你是怎样理解“通往广场的路不止一条”这句话的？
                                                                                                                                                       。
    (3)破折号在文中表示 ：                                                                                                              。    
3．在人生的旅途中，我却不止一次地遇到了与那条鲈鱼相似的诱惑人的“鱼”。    这句话最后的“鱼”为什么要加引号？它指的是什么呢？
                                                                                                                                                       。