已知函数$f\left(x\right)={\log }_{\frac{1}{2}}(x^2-ax+4a)$在$2,+\infty )$单调递减，则a的取值范围（    ）

2016年9月27日，港珠澳大桥主体桥梁正式贯通；预计2017年年底建成通车。港珠大桥是世界最长的跨海大桥，连起世界最具活力的经济区，对促进香港、澳门和珠江三角洲西岸地区经济的进一步发展具有重要战略意义，其设计建造技术先进，是中国从桥梁大国走向桥梁强国的里程碑之作。这体现了以下哲学道理（    ）

①人们能够建立有利于自身的联系

②应立足整体、统筹全局，实现发展

③人为事物的联系是科学技术的产物

④人们根据自身的需要可以建立事物新的联系

阅读短文，然后从方框中选出可以填入文中空白处的单词

    suddenly  onto  something  pushed   back  swam  friendly  towards  follow  huge

    Last month, I went to swim in the sea. I____ really far, past the rocks and out to sea.    Then I saw  ____ moving towards me. It was ____ and grey, with a large fin. It was a shark! I began to swim  ____, but he beach was too far away. The shark started to swim around me.

    I was really scared, ____ another creature appeared next to me in the water. It was a dolphin! It ____ me away from the shark. I sat on its back as it swam  ____ the beach.

Soon we were near the beach. The shark did not  ____ us. As soon as I stepped ____ the beach, the dolphin swam away. I will always remember how this ____ animal saved my life.

在成长过程中，我们会置身于不同的情景中而产生不同的情绪。请用适当语言描述你在面临以下情景时的情绪反应