在城市的很多地方都安装了摄像头，该装置的光学统主要是凸透镜，通过该装置能记录车辆及行人 ____、 ____的实像．

阅读下面一篇文章，完成小题。
                                                                                                          漫话阶梯
                                                                                                           刘心武
        ①最早的阶梯，追求的完全是连接两个以上的不同平面的功能性。但是，随着人类文明的发展，阶梯逐渐具有了心理属性，也就是说，人们建造阶梯，不仅是为了方便从一个平面上升或下降到另一个平面，而且，也是为了达到心理上的一种满足。
        ②比如北京紫禁城中轴线上的三大殿，本来，那地面是平的，可以平地起殿堂，但为了体现出天子的威严，就先起五米高的基座，再建造大殿，而分为几层的基座，再以阶梯连接，阶梯中段专供皇帝行走的部分，称御道，用最优质的汉白玉石，雕出祥云飞龙的图案。过去都称皇帝为“陛下”。“陛”是皇宫阶梯的专称。明明皇帝高高在上，臣民在他殿堂的阶梯下，似乎称他“陛上”才对，但皇帝至少在口吻上喜欢贬低自己，比如自称“寡人”，这份虚伪很有意思。
        ③中国古典建筑，不仅是皇宫，像祭坛、寺院、道观、王府等建筑群中的主体建筑，都一定要平地垒起高基座，建造有气派的阶梯，以体现出对神佛贵人的尊敬。现在仍存在的河南开封龙亭，是将这种心理需求达于极致的典型。它是在平地拔起的十三米高台上盖出一个殿堂，里面供奉着称颂“真龙天子”即“皇帝万岁”的牌位，专用于在彼处由钦差大臣宣谕“圣旨”。殿堂即“龙亭”前面的台阶分三层共72级，故意建造得相当陡峭，那夸张的造型给人强烈的视觉刺激，从而引发出心理反应。
        ④近代社会建筑中的阶梯仍可起到主导人的心理意识的作用。由吕彦直设计的完成于1929年的南京中山陵，由陵下到陵寝主体，落差为73米，设置了八个过渡性平台，一共有392级台阶（当时中国人口为三亿九千二百万）。当谒陵者在头几个平台的阔台阶上往上行走时，所望见的只是天宇，要随着一步步的攀登，那顶部的蓝瓦祭堂才会慢慢地浮现眼前。这就是建筑师利用长距离、缓爬升的阶梯，来调整谒陵者的心理，使其能够“默默想音容”，将崇敬与缅怀的情绪达于浓酽。
        ⑤北京天安门广场西侧的人民大会堂，有意将其基座与紫禁城内的三大殿取齐，但阶梯的设计，则采取了广阔通透的方式，尤其是东门阶梯的设计，很有大国气派，可以容许成百上千的人同时拾级而上，确有“让人民当家作主”的韵味。莫斯科1995年为纪念卫国战争胜利五十周年建造的胜利广场，用若干大平台来达到提升主建筑的目的，其间的阶梯故意“不起眼”，也是一种巧妙的手法，表达出一种苦尽甘来的欣慰与舒展。
        ⑥城市公众共享空间的阶梯设置，一定要突破狭隘的功能需求，营造出奇趣妙境。最成功的一个例子是罗马的西班牙广场，最出彩的就是1723年由德·桑蒂斯和斯佩基设计的那一组面对“破船喷泉”的扇形阶梯，它不仅是“视觉冰激凌”，更可以当作舞台承载多种形式的表演。已经有太多的电影利用它作为背景去表现不同时代不同人物的命运，那一组台阶实际上已经是人们熟悉的具有生命的存在。
        ⑦阶梯并非简单事物，在当下生活中，除了其实用性，“阶趣”应该是设计者考虑的重点，特别是涉及到公众共享空间时。

狗毛颜色褐色由b基因控制，黑色由B基因控制．I 和i是位于另一对同源染色体上的一对等位基因，I是抑制基因，当I存在时，B、b均不表现颜色，而产生白色．现有褐色狗（bbii）和白色狗（BBII）杂交，产生的F₂中黑色：白色为（　　）

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    At age 14, 15 and 16, the way we looked was the most important thing in the world to us. My friends and I wanted nothing less than perfection.

    In high school, we joined the gymnastics team, and our 1 became even more important to us. We had no fat, only muscle. On the weekends, we would go to the beach,  2 of our flat stomachs.

    One summer day, all my friends were at my house 3. At one point, I was running back to the pool. I 4 on a bee, and while it was dying under my foot, it stung (蛰) me. I instantly started to feel 5. That night, I began to run a high fever and my leg and foot were red, hot and swollen. I couldn't walk. I could barely 6.

    When my foot started to go numb, everyone became more 7. My foot was not getting enough blood. I had to go to the hospital, and my leg 8 as if it were badly broken. I couldn't move. All I could do was think about how soft my middle was becoming. That  9 me more than any concern over my leg.

    That would all 10 when I heard the doctors mention possibly cutting off my foot. It was still not getting the 11 supply it needed. The doctors would have to speed up their treatment.

    Never before did I have such great 12 for my foot. And walking seemed like a 13 from the gods. Less and less I wanted to hear my friends talk about 14 and who was wearing what. More and more I expected visits from other kids in the hospital, who were quickly becoming my friends.

    One girl came to visit me 15. Every time she came, she brought flowers. She was recovering from cancer and felt she should come back and 16 the other patients.

    She still had no hair, and she was swollen from the medications she had been taking. I would not have given this girl a second 17 before. I now loved every inch of her and looked forward to her 18.

    Finally, I was improving and soon I went home. My leg was still swollen, 19 I was walking, and I had my foot! When I would go back to the hospital, I often saw my friend. She was still visiting people and 20 good cheer. I thought if there was an angel on this earth, it had to be her.