机械工程专业英语赵红霞王淑珍主编 武汉理工大学出版社unit3从polymers are suitable only at low temperature到example 3-1上面
polymersare suitable only at low temperatures .some composites ,special alloys ,and ceramics have excellent properties at high temperatures.
atmosphere most metals and polymers react with oxygen or other gas ,particularly at elevated temperature.metal and ceramics may catastrophically disintegrate or be chemically attacked while others may be protected. polymers often are hardened or may even depolymerize, char,or burn.steels may react with hydrogen and become brittle.
先是这些