把下面的词语分类写下来。   

桃花  玻璃杯  杨树  梅花   榕树  

桂花    盘子  茶杯   荷花  盆    

天鹅  枫树   大雁  黄鹂  狐狸

1．                                                                     

2．                                                                      

3．                                                                       

4．                                                                      

简述函证的涵义及确定应收账款函证的数量和范围要考虑的因素。