Spiders produce silk to make their cobwebs. The silk is known for its unusual characteristics. For example, it is five times stronger than steel of the same weight and does not snap broken even if it is stretched out three times longer than its original length. With these wonderful characteristics, researchers have been researching on spider silk, and they have learned a great deal about it. For instance, spider silk is a chemical combination of proteins and is very flexible to receive impact of flying objects. Some scientists have tried to reproduce man-made spider silk (adapted from Japan's English Exam, 2008: 10)