近年来，我国最大的沙漠淡水湖红碱淖面临严重生存危机，上游地表补给河流被人坝截留，下游湖区则被开发成为旅游景区，湖水面积较鼎盛时炳缩小近半，造成湖中17种野生鱼相继绝迹，也影响了周同人们的生活用水及农业灌溉。这启示我们（    ）

①矛盾具有普遍性和不可调和性

②联系是普遍的和客观的

③人要尊重生态规律、与自然和谐相处

④发挥主观能动性能够改变自然生态规律

阅读下面短文，按要求完成各项任务．

    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 10，000kilometers on their journey from Alaska to Hawaii，swim at a relaxing speed of about 1.6kilometers 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 3months，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．

已知$\overrightarrow{a}$=（t+1，1，t），$\overrightarrow{b}$=（t﹣1，t，1），则|$\overrightarrow{a}$-$\overrightarrow{b}$|的最小值为（　　）