按要求填空。     

1．你知道下列称谓指的是怎样的朋友吗？

     布衣之交：                                                                                              

     忘年之交：                                                                                              

     贫贱之交：                                                                                              

2．“岁寒三友”是指                                                                                                

3．“花中四君子”是指                                                                                              

日本的自来水可以生饮吗？（）