D.发生冲突后应产生打闹的噪音.故选D 最恰当. 54 It is a thousand kilometers across that desert . The road is 1 ne——青夏教育精英家教网—

摘要： D.发生冲突后应产生打闹的噪音.故选D 最恰当. 54 It is a thousand kilometers across that desert . The road is 1 nearly all the way. Sometimes there is a deep sand. A driver must then put his foot down hard and drive through! There are three small 2 along the way. Vick reached the first place at ten o'clock p. m. He had his 3 in a little restaurant there. It was a warm 4 in August. Vick wanted to 5 through the night. The nights are warm enough in August, but the days are very, very 6 . He left the restaurant at 11: 30 and drove over 7 hours. There wasn't a moon, but the 8 were wonderful. There was nothing else on die road. Vick thought, "It's an empty desert. No tree, house, man. " He could 9 the endless, white road in the car's headlights. A million stars looked down on him. It was two o'clock in the morning. Vick stopped the car. He was two hundred kilometers from the 10 town: "I'll light the cooker," he thought, "and make some tea. " He got out of the car. He heard some sounds, ten or fifteen meters 11 . He could not see anything in the darkness. A man said, "Good morning. It's a 12 morning, isn't it?" The man came forward ,out of the darkness; out of the desert. Vick did not move. The man said, "You are going to 13 some tea, aren't you? I often get a cup of tea at this time. It’s two o’clock. Cars always 14 near here at this time. Sometimes I get a 15 . Now listen, and I'll tell you a story. Then you'll give me-"

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　 Eye doctors in Shanghai found out that the nearsightedness among primary and middle school students has something to do with the colour of the paper in their textbooks and notebooks．

　 The doctors suggested that yellow paper will be used to replace the white one．According to

their research，the experts found out white paper reflects too much light and easily tires a person’s eyes．The yellow paper，however，doesn’t look so sharp to a person’s eyes．In other words，it is much milder to the eyes of students who may do reading or writing for hours．

The experts’research findings were based on first．hand information and a number of scientific experiments including a new study among the students from forty-one middle schools．To make the students understand the truth，Shanghai Education Development Co．Ltd．has produced textbooks and exercise．books made of yellow paper．The books will be used in the whole city soon．

(　 )49．What does the word“replace”here mean in Chinese?

　　　 A．放置　　　　　B．重置　　　　 C．替代　　　　 D．发生

(　 )50．The doctors found out_________ caused the students’nearsightedness．

　　　 A．their studies have　　　　　　　　 B．the colour of the paper has

　　　 C．the textbooks and notebooks have　　 D．the colour of their clothes has

(　 )51．Why does white paper easily make our eyes tired?

　　　 A．Because white paper reflects too much light．

　　　 B．Because white paper gets in too much light．

　　　 C．Because white paper is always shining．

D．Because white paper is too bright．

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下列群落的演替类型中，属于初生演替的是

A．外来物种入侵，改变群落物种组成	B．弃耕农田上长出杂草、灌木
C．在火山岩上长出地衣	D．对砍伐后的森林进行封山育林

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下列群落的演替类型中，属于初生演替的是

A．外来物种入侵，改变群落物种组成	B．弃耕农田上长出杂草、灌木
C．在火山岩上长出地衣	D．对砍伐后的森林进行封山育林

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下列与生物遗传有关的叙述，正确的是（）

A．基因型为Aa的个体连续自交3代后，子代中隐性性状个体所占的比例为3/8

B．已知黑斑蛇与黄斑蛇杂交，子一代既有黑斑蛇又有黄斑蛇，若再让F₁黑斑蛇自由交配，F₂中有黑斑蛇和黄斑蛇，可据此判断蛇斑的显隐性

C．基因分离定律的实质表明，基因型为Bb的动物，在其精子形成过程中，基因B与B分开发生在初级精母细胞形成次级精母细胞时，B与b的分开发生在次级精母细胞形成精细胞时

D．用豌豆进行遗传试验，杂交时须在开花前除去母本的雌蕊，人工授粉后应套袋

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细胞通讯是指一个细胞发出的信息通过介质传递到另一个细胞产生相应的反应。细胞间的通讯对于多细胞生物调节生命活动是必需的。下图是几种细胞通讯的实例，下列说法错误的是（）

A．甲图中a是胰岛素，肝细胞上的受体与a结合后，可引起糖元的合成速率加快

B．乙图中的b是细胞表面受体，其化学本质是糖蛋白

C．丙图中的抗体是由游离于细胞质基质中的核糖体合成，内质网运输，高尔基体再加工后经外排方式分泌的，它的产生与释放都不需要能量

D．发生丙图中生理过程的e细胞至少接受过两次过敏原的刺激，它释放的d物质为组织胺

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