are now in the Levi Strauss Archival Collection in San Francisco. The jeans, which are over 120 years old, are the oldest pair of Levi's 501 jeans in the world.

　　They are almost the same as a modern pair of 501's; there are just some small differences in the detail. For instance, today's 501's have two back pockets, while the old pair just has one.

　　In 1853, a young tailor from Germany, called Levi Strauss, began working in San Francisco; Levi sold thick canvas(帆布) to miners; the miners used the canvas to make tents.

　　One day, a miner told Levi that he could not find trousers that were strong enough for work in the gold mines. Levi decided to make some trousers out of canvas. Very soon, he sold all the canvas trousers he had made! They were just what miners wanted.

　　However, the canvas was rather heavy and stiff(坚硬的). Levi therefore began to look for a different textile(织物). Soon he found a heavy textile from France; it was denim(斜纹粗棉布). Denim was a bit lighter than canvas, but is was very strong. It was ideal for miners.

　　However, original denim was almost white, and miners did not like the color! Their denim trousers got dirty as soon as they began working! Levi Strauss therefore decided to use colored denim, and he chose dark blue. In 1873, he began to make denim trousers with metal rivets(铆钉) to make them stronger. "Blue jeans" arrived!

　　Levi's jeans were so popular that his company got bigger and bigger. Soon, other firms were making blue jeans too. Miners liked them, but so did cowboys and other working men. Blue jeans became classic American working trousers. After the Second World War, jeans became popular all over the world. Today, blue jeans are made all over the world.

4. What are the old jeans found in Nevada like?

A. They are very heavy. B. They have unique and valuable decorations.

C. They are very much like modern jeans. D. They have two black pockets.

5. How were Levi's canvas trousers?

A. They were very popular. B. They were easily broken.

C. They were too expensive. D. They were quite comfortable.