人体细胞要获得氧气，排出二氧化碳，必须经过如下①②③等过程来完成：

在这些过程中，发生气体交换的有：

现代文阅读

    中国历史上选官制度的雏形，可以追溯到原始社会末期的民主制时期。《礼记•礼运》描述当时情形说：“大道之行也，天下为公，选贤与能，讲信修睦。”这里的“选贤与能”即当时自然而然形成的选拔公职人员的规程。中国古代尧、舜、禹“禅让”的传说，具体反映了当时选拔人才的情况。

    夏商以来，开始了“家天下”。（《礼记•礼运》记述当时“大人世及（即宫位世代相传）以为礼”。《尚书•盘庚》云“古我先王亦惟图任旧人共政”，可以证明这一点。这种官吏“世及”的制度，即世官制。至奴隶社会鼎盛的西周，世官制也进入鼎盛时期。那些担任王重或诸侯国官职的大小贵族，均遵照嫡长子继承的原则代代相袭，占有封地，所以也就世代垄断官职。春秋时，出于争霸斗争的需要，一些大国突破世官制的框架，实行明贤制度。到了战国，社会变革更加剧烈。随着奴隶制的崩溃和封建制的确立，惟功惟贤的新选官制度逐步建立起来，世官制时代终告结束。

    秦汉是我国古代出现的空前的大一统时期。为了封建王朝的长治久安，统治者在选官方面创立了察举制。此制选官，先经官吏察访，然后推荐给中央予以任用。荐举的标准，主要看德行、才能，而非全靠家世。汉武帝以后，此制逐渐向规范化发展。东汉未，由于“天下兴兵，衣冠世族，多离于本土，欲征源流，遽难委悉”（《通典•选举二》），故魏王曹丕接受吏部尚书陈群的建议，乃立九品中正制。这实际是一种发展了的察举制，其具体做法就是各州郡县的地方长官，将本地的人才按照丸种不同的等级推荐上来，政府据此授以官职。应该看到，九品中正立制之初，具有选贤用意，但不久即被门阀势力左右，成为世族把持政权的工具。

    隋唐之后，九品中正制遂为新兴的科举制所取代。所谓科举制，是一种考试选官的制度。它的基本特点；即“一切以程文为去留”，换言之，就是说白了能否释褐为官要凭考试成绩。此制产生于隋，确立于唐，大发展于北宋。明清时期，科举制达到了极盛。作为成熟的重要标志，是科举与学校教育的完全合流。学校储才以应科目，而科举必由学校。

    这种“学校一科举”培养选拔人才的模式，从当时世界范围来看，无疑是十分先进的。但由于明清两代的科举完全笼罩在封建文化专制主义之下，加上八股文内容空虚，形式呆板，所以科举制也开始走向没落。1904年，清政府举行了最后的一次科举考试，从此，实行了一千多年的科举制便宣告终结。

（节选自黄留珠《中国古代的选官制度》，有删改）

蔺相如对他们说____诸位请想一想____廉将军和秦王比____谁厉害____他们说____当然秦王厉害____蔺相如说____秦王我都不怕____会怕廉将军吗____大家知道____秦王不敢进攻我们赵国____就因为武有廉颇____文有蔺相如____如果我们俩闹不和____就会削弱赵国的力量____秦国必然乘机来打我们____我所以避着廉将军____为的是我们赵国啊____

已知双曲线$\frac{x^2}{9}-\frac{y^2}{m}=1$的一个焦点在圆$x^2+y^2-4x-5=0$上，则双曲线的渐近线方程为

    It was an autumn morning shortly after my husband and I moved into our first house. Our children were upstairs unpacking, and I was looking out of the window at my father moving around mysteriously on the front lawn. “What are you doing out there?” I called to him.

    He looked up, smiling. “I'm making you a surprise.” I thought it could be just about anything. When we were kids, he always created something surprising for us. Today, however, Dad would say no more, and caught up in the busyness of our new life, I eventually forgot about his surprise.

    Until one gloomy day the next March when I glanced out of the window, I saw a dot of blue across the yard. I headed outside for a closer look. They were crocuses (番红花）throughout the front lawn — blue, yellow and my favorite pink, with little faces moving up and down in the cold wind. I remembered the things Dad secretly planted last autumn. He knew how the darkness and dullness of winter always got me down. What could have been more perfectly timely to my needs?

    My father's crocuses bloomed (开花） each spring for the next five seasons, always bringing the same assurance： Hard times are almost over. Hold on, keep going, and light is coming soon.

    Then a spring came with only half the usual blooms and the next spring there were none. I missed the crocuses, so I would ask Dad to come over and plant new bulbs. But I never did. He died suddenly one October day. My family were in deep sorrow, leaning on our faith.

    On a spring afternoon four years later, I was driving back when I felt depressed. It was Dad's birthday, and I found myself thinking about him. This was not unusual — my family often talked about him, remembering how he lived up to his faith. Suddenly I slowed as I turned into our driveway. I stopped and stared at the lawn. There on the muddy grass with small piles of melting snow, bravely waving in the wind, was one pink crocus.

    How could a flower bloom from a bulb more than 18 years ago, one that hadn't bloomed in over a decade? But there was the crocus. Tears filled my eyes as I realized its significance.

    Hold on, keep going, and light is coming soon. The pink crocus bloomed for only a day, but it built my faith for a lifetime.