Every year animals all around the world take part in some wonderful journeys．Here are the stories of two amazing animal travelers．

Humpback whales （ 座 头 鲸 ） prefer a slow journey．The humpbacks，

which travel over 10，000 kilometers on their journey from Alaska to Hawaii，swim at a relaxing speed of

about 1.6 kilometers an hour．Although they don't swim fast，humpback whales travel farther than any other kinds of whale．

Every August a fantastic sight can be seen in the skies above Ontario and Montreal﹣﹣millions of amazing

Monarch butterflies （ 帝 王 蝶） beginning their 4，000﹣﹣kilometer journey from Canada to Central Mexico．In fact，the journey，

which takes about 3 months，is longer than the average （ 平 均 的 ） life of the butterfly．Finally many

of the butterflies reaching their final place are the great grandchildren or even the great great grandchildren of the butterflies who began the journey in Mexico the year before．

任务一根据文章内容，完成下列句子．（每空不超过3个单词）

Humpback whales swim at a speed of   （1）　　   an hour from Alaska to    （2）　　．They travel slowly but （3）　　among all whales．Monarch butterflies spend（4）　　   flying from Canada to Central Mexico．It lasts longer than their average life．The ones which arrive at the final place are （5）　　 or even the great great grandchildren．

任务二请用英语简要概括出本文的主旨大意，不超过10个单词．

The passage is mainly about　　．