森林中的鸟类有垂直分层现象。这种现象主要有那一因素有关（     ） 

阅读理解

    Beliefs form a big part of our lives. Successful people have always believed that they can be and will be successful in their lives, such as Michael Phelps. Many of us have seen Michael Phelps win 8 gold medals in a single Olympic Games. That has created a history for himself. Many people have admired his success and the first reaction in their mind will be, “Wow, how I wish I could be like him!” Have you ever wondered what brought him success?

    In fact, anyone can achieve what they have wanted to achieve. It is about beliefs. Everyone is a born winner. It is this belief that drives an individual to be successful in his or her own field. All successful individuals have strong beliefs and it is one of the bases for their success. If we start to believe in ourselves, the things that we can achieve will definitely give us a pleasant surprise.

    Other than having a strong belief, it is the attitude that drives the individual to create their own history. The devotion towards themselves and the drive must also be present. Imagine having a strong belief in oneself and having a poor attitude towards life. Then how would that individual turn out to be? One's attitude comprises the drive, the devotion and the desire to achieve his goals. If one has strong beliefs about the goals that he can achieve and he displays good attitudes towards them, it would be no surprise to anyone that he will be able to achieve his goals.

    Start believing in yourself and you will achieve your goals and with the right positive attitude, you will definitely be able to create the miracle that you have always dreamt of.

下列现象不可能出现在宋代的是（    ）

阅读《威尼斯商人》一文中的节选文字，完成小题。
        夏 洛 克   我的意思已经向殿下告禀过了；我也已经指着我们的圣安息日起誓，一定要照约执行处罚；要是殿下不准许我的请求，那就是蔑视宪章，我要到京城里去上告，要求撤销贵邦的特权。您要是问我为什么不愿接受三千块钱，宁愿拿一块腐烂的臭肉，那我可没有什么理由可以回答您，我只能说我喜欢这样，这是不是一个回答？要是我的屋子里有了耗子，我高兴出一万块钱叫人把它们赶掉，谁管得了我？这不是回答了您吗？有的人不爱看张开嘴的猪，有的人瞧见一头猫就要发脾气，还有人听见人家吹风笛的声音，就忍不住要小便；因为一个人的感情完全受着喜恶的支配，谁也做不了自己的主。现在我就这样回答您：为什么有人受不住一头张开嘴的猪，有人受不住一头有益无害的猫，还有人受不住咿咿唔唔的风笛的声音，这些都是毫无充分的理由的，只是因为天生的癖性，使他们一受到刺激，就会情不自禁地现出丑相来；所以我不能举什么理由，也不愿举什么理由，除了因为我对于安东尼奥抱着久积的仇恨和深刻的反感，所以才会向他进行这一场对于我自己并没有好处的诉讼。现在您不是已经得到我的回答了吗？
        巴萨尼奥   你这冷酷无情的家伙，这样的回答可不能作为你的残忍的辩解。
        夏 洛 克   我的回答本来就不是为了讨你的欢喜。
        巴萨尼奥   难道人们对于他们所不喜欢的东西，都一定要置之死地吗？
        夏 洛 克   哪一个人会恨他所不愿意杀死的东西？
        巴萨尼奥   初次的冒犯，不应该就引为仇恨。
        夏 洛 克   什么！你愿意给毒蛇咬两次吗？
        安东尼奥   请你想一想，你现在跟这个犹太人讲理，就像站在海滩上，叫那大海的怒涛减低它的奔腾的威力，责问豺狼为什么害母羊为了失去它的羔羊而哀啼，或是叫那山上的松柏，在受到天风吹拂的时候，不要摇头摆脑，发出簌簌的声音。要是你能够叫这个犹太人的心变软——世上还有什么东西比它更硬呢？——那么还有什么难事不可以做到？所以我请你不用再跟他商量什么条件，也不用替我想什么办法，让我爽爽快快受到判决，满足这犹太人的心愿吧。
        巴萨尼奥   借了你三千块钱，现在拿六千块钱还你好不好？
         夏 洛 克   即使这六千块钱中间的每一块钱都可以分做六份，每一份都可以变成一块钱，我也不要它们；我只要照约处罚。
         公   爵   你这样一点没有慈悲之心，将来怎么能够希望人家对你慈悲呢？