Printing images is easy. Just select an image of a purple robot on your PC, for example, and press print. Your home printer exactly shoots drops of ink onto a flat piece of paper, creating the robot's 2-D image. "Printing" 3-D objects is different. Take the purple robot. First select a file of the 3-D printer. Immediately, the printer begins making noise, and a nozzle   releases plastic material in thin layers. In two or three hours, a 3-D purple robot is standing before you. 3-D printing has developed to the point where printers can now create high-quality objects using a variety of materials, including metals. That means 3-D printers can now make final products that meet high industrial standards. 3-D printers are already being used to make parts for racecars and jets as well as man-made limbs and hearing aids. So far, few homes have 3-D printers. That's because 3-D printing is not only new to most people but also quite expensive. To bring 3-D printing to the masses, some retail stores   plan to offer the service. For example, the Staples chain of office supply stores has announced that it will offer 3-D printing in Europe beginning in 2013. Customers will be able to submit their own 3-D designs to Staples website for printing. After the job is done, they'll pick up their item at a nearby Staples store or have it mailed to their homes. This service is sure to encourage many more people to try out 3-D printing. What do we learn about the 3-D purple robot?
How long it can usually last How it can darken its own color How it gradually takes shape How much it costs to produce
Question: Printing images is easy. Just select an image of a purple robot on your PC, for example, and press print. Your home printer exactly shoots drops of ink onto a flat piece of paper, creating the robot's 2-D image. "Printing" 3-D objects is different. Take the purple robot. First select a file of the 3-D printer. Immediately, the printer begins making noise, and a nozzle   releases plastic material in thin layers. In two or three hours, a 3-D purple robot is standing before you. 3-D printing has developed to the point where printers can now create high-quality objects using a variety of materials, including metals. That means 3-D printers can now make final products that meet high industrial standards. 3-D printers are already being used to make parts for racecars and jets as well as man-made limbs and hearing aids. So far, few homes have 3-D printers. That's because 3-D printing is not only new to most people but also quite expensive. To bring 3-D printing to the masses, some retail stores   plan to offer the service. For example, the Staples chain of office supply stores has announced that it will offer 3-D printing in Europe beginning in 2013. Customers will be able to submit their own 3-D designs to Staples website for printing. After the job is done, they'll pick up their item at a nearby Staples store or have it mailed to their homes. This service is sure to encourage many more people to try out 3-D printing. What do we learn about the 3-D purple robot?
A. How long it can usually last
B. How it can darken its own color
C. How it gradually takes shape
D. How much it costs to produce
Answer: