Does a zoo have no useful purpose?

　　Do you agree or disagree with the following statement? A zoo has no useful purpose. Use specific reasons and examples to explain your answer.

　　写作思路展开结构分析

　　不能同意，no是绝对修饰词，因此一旦出现肯定是要否定的。至于公园的useful purpose有很多，大家可以任选几条来展开，当然由于现在有许多公园因为经费不够而虐待动物的新闻报道，因此大家也可以举例后指出确实有一些动物园不值得保留下去。

　　本话题高分范文赏析

　　Perhaps one of the most blameworthy factors that make some people raise the eyebrow to zoos and criticize that "A zoo has no useful purpose" is its exorbitant price to maintain. However, it is too hasty to say so, since most zoos have their significance, both educational and scientific. Modern zoos act as centers of education and are designed to make learning about animals an interesting and enjoyable experience. They provide visitors with the chance to see rare creatures, such as tigers, zebras, penguins, and giant pandas, which come from many different parts of the globe. Zoos also introduce people to their own local wildlife, offering a valuable learning experience in an increasingly urban world. At the same time, most zoos provide educational programs aimed at a wide range of ages. A visit to a zoo provides children an opportunity to see and touch animals other than household pets. For older schoolchildren, many zoos conduct classes or day trips that focus on different aspects of animal biology and the impact of humans on animal life.

　　Modern zoos also have their scientific imports and can function as a sanctuary for endangered animals and therefore help maintaining ecosystems. In zoos scientists can create an animal population that can become self-sustaining in the wild. An example of a successful reintroduction to the wild is the David's deer. This Asian deer was native to marshlands in northeast China before its habitat was destroyed more than 800 years ago and it became extinct in the wild. Since that time the species has been bred in zoos in China and later in Europe. In 1985 four David's deer were released to the wild in a protected animal reserve in China, where they are now breeding successfully.

　　On the other hand, some experts warn against placing too much reliance on zoos as biological "arks," where species can be protected regardless of environmental changes outside. Critics warn that zoos, like all human institutions, are vulnerable to unforeseen events, such as disease, fires, and financial or social upheaval. More significantly, the number of species that zoos can protect is strictly limited. Today's zoos are home to no more than a few thousand species—only a fraction of the world's animal life. Zoos already have to perform a delicate balancing act between large, crowd-attracting animals and threatened animals that have less visitor appeal. During the 21st century, zoo experts will face even harder decisions about which species they can afford to save.