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  3. How are jigsaw puzzles made? The method of making a jigsaw puzzle hasn’t changed much since its invention in the late 18th ce

How are jigsaw puzzles made? The method of making a jigsaw puzzle hasn’t changed much since its invention in the late 18th ce

admin2010-06-18  58
问题                      How are jigsaw puzzles made?
   The method of making a jigsaw puzzle hasn’t changed much since its invention in the late 18th century: an image is mounted on solid material and cut into a bunch of pieces. The first puzzles were made of wood and cut with a jigsaw, hence the name of the game.
   You can still buy puzzles made Of wood, but the type you’re probably most familiar with is die-cut cardboard. The die-cut press, in wide use in the United States by the 1930s, according to puzzle historian Anne D. Williams, exerts 500 tons of pressure to hold a board in place while a steel-rule die cuts it into pieces. The die consists of pieces of metal that have been shaped to form each piece in the puzzle — much like a cookie cutter punches out a shape in dough. Recent innovations include the use of lasers and computer-contro11ed water jets to cut puzzle pieces.
   Some manufacturers still have their puzzle pieces drawn by hand; others use a computer to ensure that only two pieces will fit together exactly. Puzzle styles have evolved, however, from maps and flat images to three-dimensional objects and trick puzzles. In some of these complicated puzzles, several pieces will fit together securely, but only one combination of pieces yields the correct solution to the puzzle.
When was the jigsaw puzzle first invented?
选项 A、Not earlier than 1800.
B、1930’s.
C、1750 to 1799.
D、Not known.
答案C
解析
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