摘要：7．表示“同一 .相当于the same.如: The two boys are of an age．那两个男孩年龄一样大 Cotton of a kind was stored together in a house． 同种棉花被一起贮藏在一间屋子里.
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（9分）某同学的肝功能检验结果显示：乙肝抗原呈阴性(－)，乙肝抗体呈阳性(＋)，（说明：“＋”表示有，“－”表示没有）
。请回答下列有关问题：
（1）该同学并没有注射过乙肝疫苗，就此检验结果请你分析可能的原因是 。
（2）用图解表示乙肝病毒（含有DNA）感染人体过程中的遗传信息的流动方向： 。
（3）由乙肝病毒外壳蛋白制成的乙肝疫苗，注入机体之后，将作为__________物质，使__________被激活而增殖分化形成浆细胞和__________。
（4）该同学在踢足球时不小心被铁钉扎破了脚，及时注射了破伤风抗毒素进行治疗，已知破伤风杆菌可阻止神经末梢释放甘氨酸，因而能引起肌肉痉挛和惊厥
。据此分析甘氨酸相当于一种________，它能使下一个神经元的 信号向 信号转换过程受阻。
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。请回答下列有关问题：（1）该同学并没有注射过乙肝疫苗，就此检验结果请你分析可能的原因是 。
（2）用图解表示乙肝病毒（含有DNA）感染人体过程中的遗传信息的流动方向： 。
（3）由乙肝病毒外壳蛋白制成的乙肝疫苗，注入机体之后，将作为__________物质，使__________被激活而增殖分化形成浆细胞和__________。
（4）该同学在踢足球时不小心被铁钉扎破了脚，及时注射了破伤风抗毒素进行治疗，已知破伤风杆菌可阻止神经末梢释放甘氨酸，因而能引起肌肉痉挛和惊厥
。据此分析甘氨酸相当于一种________，它能使下一个神经元的 信号向 信号转换过程受阻。
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小明家台灯的插头插在如图所示的插座上，插座上有一个开关和一个指示灯（相当于电阻很大的灯泡）。若插座开关和指示灯用S1、L1表示，台灯开关和灯泡用S2、L2表示。小明断开或闭合S1、S2时，记录现象如下表。则符合事实的电路图是
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（4分）我国北方早春育苗常用温床，电热温床是其中的一种。电热温床是这样制成的：先将床土挖去约20cm厚，床底铺一层麦秸或锯末，再铺一层塑料膜。将电热线按10cm间距，均匀地铺在塑料膜上，再把床土放回，这样电热温床就做成了。
电热温床的温控仪相当于一个阻值随温度变化的可变电阻，利用它可以根据温度自动控制通过电热线的电流，从而实现温床温度的自动控制。使用时应该把温控仪与电热线______联。电热线不能打结、交叉或重叠，否则可能由于______________________________而发生危险。这种方法是利用_______________获得适宜幼苗生长的温度。 查看习题详情和答案>>
电热温床的温控仪相当于一个阻值随温度变化的可变电阻，利用它可以根据温度自动控制通过电热线的电流，从而实现温床温度的自动控制。使用时应该把温控仪与电热线______联。电热线不能打结、交叉或重叠，否则可能由于______________________________而发生危险。这种方法是利用_______________获得适宜幼苗生长的温度。 查看习题详情和答案>>
Is the world too crowded? Well, that’s a hard question to answer. It’s all a matter of perspective(视角).In Montana, you might drive for a mile in any direction and not see another human being. In Macao, 60,000 people live in every square mile!
What is true is that the world’s population doesn’t stay the same. It has been increasing at a very fast rate(比例).That’s in part because in each generation(代) these are more people who then have children than in the last generation.
Five hundred years ago, the population of the world was about 460 million. In 1900,the world’s population was under 2 billion(十亿).Right now it is doubling every 40 years. That means, if this rate of growth continues, when you are a parent, there will be twice as many people on earth as there are now. Wow! Now that’s a whole lot of people! Soon the world’s population will probably reach 7 billion. Some people worry about that! But there is a lot of disagreement about just how many people on earth equals(相当于) too many people. But everyone agrees that the more people there are, the more resources(资源) the world needs to feed, house and take care of all of them, and the more need there is to think carefully about how we live and use the earth’s resources.
【小题1】From the first paragraph we can know that ________.
| A．Montana is too crowded |
| B．Macao is too crowded |
| C．the world is too crowded |
| D．the world is not too crowded |
| A．people live longer than before |
| B．there are less wars than before |
| C．medicine is developing faster than before |
| D．more couples now would like to have children than before |
| A．450 million. | B．about 2 billion. |
| C．40 billion. | D．7 billion. |
| A．find more resources |
| B．use more resources |
| C．think about our ways of living |
| D．move to other places |
| A．thinks the world already has too many people |
| B．thinks the world can feed no more than 7 billion people |
| C．is not sure when the world’s population will reach 7 billion |
| D．is not sure what the largest population that the world can feed is |