【中外历史人物评说】

阅读材料，回答问题。

材料一 前139年张骞首次出使西域，期间历经千辛万苦，前后长达十三年。在经过河西走廊时，被匈奴发现并俘获。张骞被囚禁十余年后，终于寻机逃出来。经过大宛（今费尔干纳）、康居（今撒马尔罕）到了阿姆河上游，终于找到了大月氏。大月氏在这一带安居乐业，再也不想去跟匈奴报仇了。张骞回程中又被匈奴人抓住，所幸他再次逃脱，回到了长安。元狩四年（前119）张骞第二次出使西域的使命是与伊犁河流域的乌孙人结成联盟，“厚赂乌孙，招以东居故地”，“以断匈奴右臂”。却正好乌孙发生内乱，又未能实现结盟的目的。

材料二 汉武帝派张骞出使西域的最重要的目的带有军事安全战略性质，即西汉王朝迫切希望与西域大月氏等国建立联盟，共同攻打匈奴，以“断匈奴右臂”。其实张骞出使西域的最重要的战略目标并没有达到……。但“无心插柳柳成荫”，张骞出使西域却使横贯东西方的丝绸之路被正式开通了。所以，司马迁将张骞出使西域的壮举视为“凿空”之行。张骞……出使西域则更多地带有畅通丝绸之路的战略含义。……他奉汉武帝之命访问西域诸国，密切了西汉和西域诸国的政治、经济和文化联系。张骞出使以后，西域与中原建立了密切的联系，西域历史成为中国历史的一部分，中亚草原成为连接中国与西方文明的桥梁。

——摘自（《从“凿空西域”到“一带一路”：丝绸之路的历史变迁与当代启示》中国社会科学院中国边疆研究所所长邢广程访谈）

     We always celebrated Dad’s birthday on Thanksgiving Day, even after he entered a nursing home. When we knew it might be his last birthday, the whole family decided to get together for a huge birthday celebration at the nursing home.
     Dad was a good storyteller and we were always his listeners. During a quiet moment, I announced it was now Dad's turn to listen to stories for a change. I wanted everyone to tell Dad what we loved about him. The room became quiet. Then one after another, people told stories from their hearts, while Dad listened with tears in eyes.
      Everyone seemed to have more than one story. Even the little grandchildren could't wait to tell Dad why they loved him. For a man who had been kind to so many hundreds of people in his life, here was our chance to tell him how much we love him. A few months later, at Dad's memorial service, we more fully realized what we had given to Dad that night. Those are the stories people normally tell at a funeral (葬礼) after a loved one is no longer alive to hear the words. They tell stories, full of tears. But we had given those memories to Dad in his life, and we had told them through laughter, together with hugs and joy. He had them to hold and enjoyed them from time to time in his mind during his last days and months.
     Words do matter, and they are enough. We just need to say them or to speak them publicly the ones we love. That's the ways to give back love and that's our chance to celebrate a person in his or her life. 

    The world renowned British Physicist Stephen Hawking who tried to explain the mysteries of the universe to millions of people passed away on March 14th, 2018 at the age of 76. His family said he died peacefully at his home in Cambridge. Professor Hawking used wheelchair and was able to speak only through a computer synthesizer(合成器), having been suffering from a rare form of motor neuron disease as a young man. Despite being given only a few years to live, he wrote popular science books for several decades. A film about his life The Theory of Everything won an Oscar for the actor Eddie Redmayne who portrayed him.

    Stephen's daughter Lucy spoke about her father's love of the limelight in 2012. She said, “Actually my father is also a showman. He loves a big show, a big stage and bright light, whether it's him on stage or whether it's watching the spectacle.”

    Stephen Hawking's death was announced in the statement by his children who said they will miss him forever. They said his courage and brilliance inspired people across the world. Many leaders from different countries paid tribute(致敬) to him including the Indian Prime Minister Narendra Modi, who said Professor Hawking had made the world a better place.

实验桌上有底面积已知为S的柱形容器一个，足量的水，细线若干，不同体积的石块六个，刻度尺和弹簧测力计各一．请你利用以上器材设计实验证明：“水对容器底部压力的变化量△F_压等于物体浸没时受到的浮力F_浮”．