阅读理解。 The Chinese were the real inventor of printing. Centuries ago they carved messages on a stone and then sprinkled (撒) sooty(煤炭的) dust over it. When they put a small piece of paper over the stone and rubbed the paper, the sooty lines were reproduced on it. Some of these first printed papers have been preserved; the oldest ones known to exist are more than one thousand years old. Printing with carved stone blocks was the only kind of printing known for centuries. Then, about eight hundred years ago, a Chinese printer, Bi Sheng, had a clever idea. Instea d of carving a whole message on a single big block of wood or stone, he formed separate Chinese words or characters out of bits of clay(粘土). By putting the clay pieces together in rows in a box, he could print just as before. But when he finished, he could keep all the separate pieces of clay and use them again. Bi Sheng's movable type was a great step forward, but his method was not generally adopted. Movable type did not come into use in Europe until it was invented there centuries later. The Europeans had been totally ignorant of the printing traditions of the Chinese. 1. The oldest pieces of printed paper in existence date back ______. A. 800 years B. more than 1000 years C. more than 2000 years D. 500 years 2. Bi Sheng used clay to form ______. A. large tablets for writing B. messages C. individual words or characters D. small statues 3. These pieces of clay were ______. A. easily lost B. broken C. reusable D. disposable 4. Europeans adopted printing after they ______. A. reali zed stone carving was inadequate (不够的) B. had learned about it from the Chinese C. had copied Chinese printing D. had invented it themselves