正如我们在第7天和第8天所介绍的，谋篇布局的方法有很多种，今天我们就这方面所学的知识加以操练。
One for all， all for one.
我为人人，人人为我。
「活动教室」
Passage 1.
请用一支彩笔把下面文章中首段和末段中的背景内容划出来，找出这两段的中心思想。
Zoo Animals
Human beings have always wanted to hunt wild animals， not only for food or sport， but also to keep in captivity. Many cities have zoos with a large collection of animals on show. Some zoos such as the Singapore Zoo and Taronga Park in Sydney are famous tourist attractions. Zoos have both positive and negative aspects. Sometimes keeping animals in captivity benefits the humans and sometimes the animals benefit； but， at times， the animals suffer as a result of their confinement.
Zoos give most people in the world their only opportunity to study wild animals at close quarters. Even people who are lucky enough to go on a wildlife safari in Africa are not able to see animals at such close range. In some zoos in Australia it is possible for visitors to wander among animals such as kangaroos and deer and feed them by hand. For urban children it is a delight to actually see the animals which they have seen on television. Zoos also provide scientists with the opportunity to study animals over a period to time.
Scientific research conducted on zoo animals adds to human knowledge， and it benefits animals too. Treatments for diseases which have been developed for animals in captivity can be made available for all animals. Another advantage of having zoos is the possibility they provide for captive breeding programs. Animalsspecies which are endangered or on the edge of extinction can be encouraged to breed within a controlled， protective environment. This is crucial for such animals as white rhino， pandas and tigers.
However， some animals in zoos are not treated well. Sometimes their living quarters are cramped and unnatural. It is common to see tigers and panthers pacing the floors of their cages for hours bang their heads against the walls of their enclosure. Their plight can be much worse in countries where economic hardship causes their food to be rationed and their health neglected. In some parts of the former Soviet Union keepers struggle to look after the animals with little funding even for their own wages.
This is no doubt that people will continue to want to be able to see wild animals in captivity. However， people should make sure that the animals that live in a zoo and give us so much pleasure have a good life themselves.
答案与解析：
Background information in the introduction paragraph：
答案：Human beings have always wanted to hunt wild animals， not only for food or sport， but also to keep in captivity. Many cities have zoos with a large collection of animals on show. Some zoos such as the Singapore Zoo and Taronga Park in Sydney are famous tourist attractions.
解析：通常介绍性材料的内容多出现在文章的第一段，这篇文章也不例外。本文主要讨论的是人与动物园中动物的关系，文章的导入部分为第一段的前三句。介绍了人类对于动物的一贯做法，即除食用、运动等目的之外，人类喜欢狩猎，并把动物囚禁起来。这样一来很多城市中的动物园的存在就变得合理化了，有些甚至成了当地著名的旅游名胜地。以上内容就可看作本文的背景内容，主题句出现在这部分之后。Background information in the conclusion paragraph：
答案：This is no doubt that people will continue to want to be able to see wild animals in captivity.
解析：这句话是出现在最后一段，往往也是结论段的对客观事实的陈述，属于基本情况范畴，故为本题的答案。它揭示了人们对于动物园中动物的依赖之情，在文章的正文部分作者已将动物园存在的利弊一一列举出来，那么要想延续人们囚禁野生动物的愿望关键在何处呢，这就要看本段的主题句了。The main idea in the introduction paragraph：
答案：Zoos have both positive and negative aspects.
解析：这句带有评论性的语言很显然就是这部分的主要内容，甚至可以看作是本文的中心内容。在此之后的内容是对这句话的解释说明。The main idea in the conclusion paragraph：
