单选题 Kite flying is the sport of sending up into the air, by means of the wind, a light frame covered with paper, plastic or cloth. The frame can be one of many different shapes and is attached to a long string held in the hand or wound on a drum. Kites have a long history of practical application and many different types of kite have been developed to serve various purposes.
The ancient Chinese used bird-kites to carry ropes across rivers and valleys. The current folding kite which will dive excitingly is an improved type of such a kite. With its long flat body and single pair of birdlike wings, it looks just like a large bird in the air. The modem version is usually made of tissue-paper rather than the traditional silk.
Man-lifting kites were developed in ancient times, again by the Chinese, for getting information from walled cities and army camps In fact, as recently as World War Ⅱ, German U-boats flew kites from their towers to lift people into the air to watch the land. These kites, which are no longer in existence, were made of light-weight cloth. They were much larger and stronger than the Chinese ones. Their design, however, was simply that of the cutter kite. Smaller in size, this type of kite is still very popular as a toy for children, being easy to make with a diamond-shaped frame, no wings and brown-Raper covering.
Box-kites are another type of kite found in toy shops today. The first box-kite, named for its box-like body, was developed in the nineteenth century to test theories of flight and this type of cotton-covered kite greatly assisted the success of early aeroplanes.
These kites are the ancestors of a heavier version of the box-kite, called the double box-kite, which consists of two main sections, placed side by side. Developed for the peacetime purpose of fishing in strong sea wind, it is the only modern kite described which has practical value. A long-lasting plastic material has to be used for this kite, which carries fishing lines.