Five cloned pigs，whose organs are much less likely to be rejected(排斥) by a patient，have be

Five cloned pigs，whose organs are much less likely to be rejected(排斥) by a patient，have been born in the U．S.
More than 62,000 people in the U．S. alone are waiting to donated hearts，lungs and so on.The number of human donors falls far short of .Pig organs are of a(n) size to human organs，and some scientists hope they might be used to help meet the .But previous attempts to transplant pig tissue into humans have .
The five pigs a gene that adds a sugar to the surface of pig cells.The sugar would immune(免疫的) rejection of the tissue.“This advance provides a near­time for overcoming the problem that there is not enough human organs for transplants，”says an expert.“This is the gene for overcoming the stage of rejection.”
，scientists warn that much more work is necessary organs from copies of the pigs could be transplanted into humans.Human genes will need to be added，to rejection of the organ in the long term.There are also that pig viruses could infect patients.
Cloning techniques were to the production of the pigs.Genes can only be knocked out(去除) in a single cell.Cloning of these single cells then allowed the of a whole animal in which the gene was knocked out in every cell.But the PPL researchers have in knocking out only one copy of the gene.The team will now attempt to knock out both copies of the gene.
The team will also tests to investigate whether a virus from the pigs could infect human cells.“Although a lot of the work is very ，we’re still very far off being able to grow an organ，” says Julia，who is working on this project and quite to creating similar knock­out pigs with researchers at the University of Missouri.
【小题1】A．exchangeB．checkC．possessD．receive【小题2】A．discussionB．demandC．doubtD．distance【小题3】A．beneficialB．identicalC．similarD．certain【小题4】A．shortageB．conditionC．satisfactionD．argument【小题5】A．continuedB．failedC．finishedD．paused【小题6】A．lackB．includeC．makeD．change【小题7】A．leaveB．causeC．blockD．destroy【小题8】A．supplyB．ambitionC．contributionD．solution【小题9】A．only B．rareC．keyD．safe【小题10】A．lastB．wholeC．nextD．early【小题11】A．HoweverB．ThereforeC．BesidesD．Finally【小题12】A．becauseB．beforeC．ifD．after【小题13】A．prevent B．ignoreC．judgeD．weaken【小题14】A．regretsB．emotionsC．concernsD．interests【小题15】A．simpleB．vitalC．unusualD．basic【小题16】A．collectionB．applicationC．receptionD．creation【小题17】A．delightedB．succeededC．joinedD．believed【小题18】A．conductB．planC．designD．study【小题19】A．perfectB．strangeC．excitingD．disappointing【小题20】A．opposedB．usedC．devotedD．suitedC

(答案→)C 解析：【小题1】　D解析　由本段内容可知，应是等待接受器官的移植。【小题2】　B解析　器官捐献不能满足人们的需求，demand符合语境。【小题3】　C解析　根据上下文可知，克隆猪的器官可以被移植到人体内，它们的器官应该和人类的器官大小相似。【小题4】　A解析　根据本段第二句“The number of human donors falls far short of .”可知，克隆猪的器官是为了弥补人类可移植器官的不足。【小题5】　B解析　上一句提到科学家期望克隆猪的器官能够应用于人类器官移植领域，but表示转折，说明以前类似的试验失败了。【小题6】　A解析　由下文“...a gene that adds a sugar to the surface of pig cells.The sugar would immune(免疫的) rejection of the tissue.”可推测，这一基因会导致不好的结果，又根据“‘This advance provides...’”可知，这五只克隆猪没有这一基因，因此选lack。【小题7】　B解析　根据上下文可知，这种糖分可能会使器官产生免疫排斥，cause符合语境。【小题8】　D解析　根据后面overcoming the problem的提示，可知对人类可移植器官不足的问题提供了一个解决办法。【小题9】　C解析　根据上文“...a gene that adds a sugar to the surface of pig cells.”可知，这一基因对克服器官排斥问题很关键，所以选key。【小题10】　D解析　根据下一段第二句“Human genes will need to be added，to rejection of the organ in the long term.”可知，对这一基因的处理只能解决器官排斥早期的一些问题。【小题11】　A解析　根据下文“...scientists warn that much more work is necessary...”可知，本段内容与上一段意思是转折关系，所以用however。【小题12】　B解析　根据下文“Human genes will need to be added...”可知，在克隆猪的器官可以移植到人体内之前，还有很多工作要做，所以用before。【小题13】　A解析　根据上下文可知，科学家们的这些工作是为了防止器官排斥。【小题14】　C解析　由句意可知，猪身上的病毒可能会感染病人，这是人们所担心的。【小题15】　B解析　这五只猪是克隆动物，显而易见，克隆技术对繁育出这几只猪至关重要，vital符合语境。【小题16】　D解析　基因的去除只有在单个细胞中才能进行，克隆这些单细胞然后再将其培育成一只完整的动物，这样动物身上的每个细胞中的这种基因就都被去除了，creation符合语境。【小题17】　B解析　根据下文“The team will now attempt to knock out both copies of the gene.”可知，PPL researchers已经成功去除这种基因的一个副本。【小题18】　A解析　句意为：这一团队还将进行试验研究克隆猪身上的细菌是否会感染人体。conduct tests进行试验。【小题19】　C解析　although表示让步，根据主句“‘we’re still very far off being able to grow an organ，’”可知，exciting符合语境。【小题20】　C解析　Julia致力于培育这种去除基因的克隆猪，devoted符合语境。

感谢回答，我学习了