double metallic standard

例句：

1. 1. The double-decker bus is a popular mode oftransportation.
   双层巴士是一种受欢迎的交通工具。
2. 2. She hastwo children, each with their own room.
   她有两个孩子，每个都有自己的房间。
3. 3. Thedouble-glazed windows provide better insulation.
   双层玻璃窗户有更好的隔热效果。