What are materials? Materials are the matter of the universe.These substances have properties that make them useful in structures,machines,devices,products, and systems. PDF文件使用"pdfFactory Pro”试用版本创建w,fineprint.com,cnWhat are materials? Materials are the matter of the universe. These substances have properties that make them useful in structures, machines, devices, products, and systems. PDF 文件使用 "pdfFactory Pro" 试用版本创建 ùwww.fineprint.com.cn