把古诗补充完整。

                                                                               赠汪伦

                                                                         （唐）李白

                                                                 ______乘舟将欲____，

                                                                 忽闻岸____踏歌____。

                                                                 桃花潭____________，

                                                                 不及汪伦送________。  

拗折的需求曲线是表示一个寡头垄断企业当它要提价时，对手企业也同时提价。