5. Find the unnecessary

When we press a piece of rubber we change its shape. But as soon as we stop pressing, the rubber springs back to its first shape; we therefore say that rubber is elastic. Rubber was first used to make rubber balls. In 1492, Columbus sailed from Spain and discovered America. One of the many strange things which he and his men saw in America was a game played with rubber balls. They noticed that the rubber balls bounced much better than the balls which they had used in their own country. When they sailed home again they told their friends that the balls were made from the gum of a tree. Hundreds of years had passed before rubber was used in Europe and other parts of the world. Small pieces of rubber were brought to Europe, and kept by people who liked to collect strange things; but no one thought that rubber could be useful. Then an artist found out that rubber would rub out pencil marks. That was one of the first uses of rubber, and that is how it came to be called 'rubber'. Rubber trees grow only in countries where it is very hot and very damp. These countries are near the equator; so it was in the countries near the equator that men went out to hunt for the rubber trees. It was not easy to find the trees. In those hot damp lands, trees of many kinds grow so close together that it is difficult to travel through the forests. The men who were hunting for rubber trees found them growing wild in South America, in Central America, and in West Africa. Nearly all the world's rubber came from the great forests of America and West Africa. нужен качественный перевод!!!