边长为4cm的正方形ABCD绕它的顶点A旋转180°，顶点B所经过的路线长为____ cm．

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                                                                                爱与孤独
      ①爱和孤独是人生最美丽的两支曲子，两者缺一不可。没有爱的心灵会孤独，未曾体味过孤独的人也不可能懂得爱。由于怀着爱的希望，孤独才是可以忍受的，甚至是甜蜜的。
      ②不止—位先贤指出，—个人无论看到怎样的美景奇观，如果他没有机会向人讲述，他就决不会感到快乐。人终究是离不开同类的。一个无人分享的快乐绝非真正的快乐，而一个无人分担的痛苦则是最可怕的痛苦。所谓分享和分担，未必要有人在场。但至少要有人知道。永远没有人知道，绝对的孤独，痛苦便会成为绝望，而快乐——同样也会变成绝望！
      ③交往为人性所必需，人生之常态，而它的分寸却不好掌握。帕斯卡尔说：“我们由于交往而形成了精神和感情，但我们也由于交往而败坏着精神和感情。”我相信，前—种交往是两个人之间的心灵沟通，它是马丁•布伯所说的那种“我与你”的相遇，既充满爱，又尊重孤独；相反，后一种交往则是熙熙攘攘的利害交易，它如同尼采所形容的“市场”，既亵渎了爱，又羞辱了孤独。相遇是人生莫大的幸运，在此时刻。两颗灵魂仿佛同时认出了对方，惊喜地喊出：“是你！”人一生中只要有过这个时刻，爱和孤独便都有了着落。

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       Q：My neighbor's back garden is an overgrown jungle for a few months and I believe I've got rats under my shed as a result. I have been troubled by such a bad scene for a long time.Can I make my neighbor manage her back garden?

       A：Firstly, you will need to contact a pest control company to deal with the rat problem, which could be a danger to you and your family. The pest control company will produce a report detailing the issue and give an opinion as to whether your neighbor's overgrown garden has caused the rats to run in all directions.

      If that is the case, then you should get in contact with your neighbor in an attempt to resolve the issue. You should discuss your concerns with all your heart with your neighbor and advise her of the situation and of the findings of the pest control company.

     You do not advise whether the house is rented out or perhaps your neighbor is elderly without the ability to deal with the problem personally. If your neighbor is uncooperative, then I would advise you undertake the following action.

     Get in contact with your local authority or the Department of Environment, Community and Local Government and report your concerns, particularly the pest issue immediately.You could also contact the HSE, more especially if children use the garden and are likely to come in contact with rat droppings etc, which can be dangerous to them. If the above is not successful, you should inform your lawyer and take advice. You should also document your conversations with your neighbor.

     If your house is for sale, ask your agent to prepare a report outlining the effect of the next door garden on value, but also outlining the effect on marketability and the negative impact on viewings.

Notes：

①uncooperative adj.不愿合作的，不愿配合的　②authority n．权力，职权，官方，当局　③marketability n．可销售性