우선 이건 상당한 실력이 필요한거 같네요

(1)
Coral reefs are complex, multi-story structures with holes and crevices shared by various creatures.

If a coral reef can be thought of as a metropolis of the sea, then a coral colony can be thought of as an apartment building with many different rooms and hallways that house different marine species.

The actual architects of coral reefs are hard or stony corals, which are referred to as hermatypic or reef-building corals.

As the polyps of stony corals grow, they produce limestone for their skeletons.

When they die, their skeletons are left behind and are used as foundations for new polyps, which build new skeletons over the old ones.

An actual coral mound or tree is composed of layer upon layer of skeletons covered by a thin layer of living polyps.

Other types of animals and plants also contribute to the structure of the reef.

Many types of algae, seaweed, and even mollusks like giant clams and oysters add to the architecture of a coral reef.

When these organisms die, they also serve as foundations for new corals.





(2)
A community consists of the populations of various species that live together in the same place.

When a natural area has been disturbed, for example, by a volcanic eruption, an earthquake, or a forest fire, a new community does not spring into exstence overnight but develops gadually through a series of stages.

The process of community development over time, which involves speicies in one stage being replace by other species, is called ecological succession.

Ecological succession is usually described in terms of the changes in the types of vegetation of an area, although each successional stage also has its own characteristic kinds of animals.

The time intervals involved in ecological succession are on the order of tens, hundreds, or thousands of years, not millions of years as in the evolutionary time scale.





(3)
Many villages and towns were formed over the years by chance.

Sometimes. following their roads makes one think they were originally cow paths.

Stirling was a carefully planned town before the first settler set foot on it.

It was patterned after a rather famous city plan designed in 1833, the Plat of Zion by Joseph Smith.

The plan was truly visionary, and so adaptable to city planning in general that it was offcially recognized by the 30,000 members of American Planning Association.

This plan, designed for 15 to 20 thousand people, incorporated such ideas as modern zoning, land use regulations, and square wide streets.

Stirling, however, failed to meet the dreams and expectations of its founders.

Interestingly enough, this is one of the reasons Stirling has been designated as a Canadian National Historic Site.





(4)
The increasing wail of an ambulance\'s siren as it approaches and the corresponding decreasing pitch as it departs are common examples used to explain the Doppler effect.

The sound waves in front of the siren compress when the source of the waves moves in a line.

Those behind the siren are stretched out in an opposite fashion.

In a parallel way, emitted light such as that from a star also changes appearance depending upon the observer\'s position relative to its movement.

However, instead of a change in pitch like the sound of the siren, light changes color; it turns red as it recedes and blue as it approaches.

The first to understand the implication of this was the eminent American astronomer Edwin Hubble.





(5)
After the invention of the cotton gin, the yield of raw cotton doubled each decade after 1800.

Demand was fueled by other inventions of the Industrial Revolution, such as the machines to spin and weave it and the steamboat to transport it.

By mid-century, America was growing three-quarters of the world\'s supply of cotton, most of it shipped to England or New England where it was manufactured into cloth.

During this time tobacco fell in value, rice exports at best stayed steady, and sugar began to thrive, but only in Lousisiana.

At mid-century, the South provided three-fifths of America\'s exports, most of it in cotton.