1. 根据逻辑关系判断

      The phone bought /was bought in the supermarket.

      分析：The phone 应该是被买来，所以bought是done过去分词，所以这句话的谓语动词应该选择was bought。                                

   2. 根据及物动词或不及物动词判断

      It established / was established to honor the president.

      分析：establish是及物动词，所以它后面应该有宾语，但我们

           发现此句中的establish后面并没有宾语，由此可判断

           establish在此句中是done，所以这句话的谓语动词应该

           是was established。

  例题             

  One of the most beautiful trees in North America, the chestnut tree  

  brought nearly to extinction by a fungus during the chestnut blight

  of 1909.

   (A).    tree brought nearly to extinction by a fungus

   (B).    tree was brought nearly to extinction by a fungus

  分析：根据逻辑关系判断，the chestnut tree应该是被 fungus导致

        灭绝，所以brought在此句中应该是done，由此可知，此

        句的正确答案应该选B.