A young lady was sitting in her garden under a tree drinking tea. _________, something white fell and _________ in her drink. It was a cocoon (茧). As the cocoon rumbled (发出隆隆声) in the hot _________, she realized that it was made from a long, strong and soft _________. She started thinking about how to _________ the new material. Does this story sound a bit _________? It does remind me of Isaac Newton, having the _________ of the law of gravity while sitting under an apple tree after he was _________ on the head with a piece of falling fruit.

The story of the young woman and her tea is a popular Chinese legend (传说) about _________. When silk was first invented, silk clothing was __________ by the rich people, and it was a status symbol. But over time its use spread and a wider range of social classes __________ wearing silk clothes.

As the production of silk increased, it began to be put into industrial __________ and became a part of musical instruments, fishing lines, even wrap paper and trade business.

Silk was __________ traded and spread all the way from China to India and through Central Asia to the Middle East. It was the longest trade route across land, and it allowed early __________ between Europe and China. Italy became one of the major producers of silk and it’s __________ some of the world’s finest silk cloth is made even today.

It’s 3000 years ago, and people make the things they need by hand. They use metals, such as bronze and tin, to make tools and weapons, but these metals are hard to find. A group of people called the Hittites begin ________with a unique rock called iron ore, which is easy to find and mine. They make a(n) ________: By heating this rock, they get a new metal, called iron, which they can shape into sharp knives and other tools. The Hittites see little use for iron, ________, beyond making these simple tools. Never in their wildest dreams can they imagine the ________ iron will have on the world. But it’s where the story of the ________ begins.

This early form of iron isn’t strong enough for large things like buildings. Over thousands of years, though, people learned ways to make iron stronger. They ________ their rock ovens, raising the temperature and adding different minerals to the ore. Each experiment ________ the process, as people learned to change iron into carbon steel.

Finally, in 1855, an English engineer named Henry Bessemer invented a machine that turned large amounts of iron into steel in just minutes, which is strong and can be made into nearly any ________, including frames for tall buildings. Still the first skyscraper wasn’t built for almost 30 years. Why? Nobody wanted to walk up and down all those stairs. Tall buildings need a way to elevate people and objects. Although elevators existed, they weren’t safe enough for people. Pretty soon, seeing steel cables supporting bridges led people to ________ how steel cables could make elevators safe. And with safe elevators, you could build much ________ buildings. In 1884, the Home Insurance Building, the first skyscraper, rose. It was 138 feet high — higher than any other building at that time. It had ten storeys and four elevators — a miracle at the time!

The mighty skyscraper is much more than a building, though: It’s a ________ of what we can accomplish when we just try things. Inventions come from ideas, big and small, and from people old and young. So put on your thinking caps, because the great inventions of the future ________ your ideas today!