Some progress is being made-aluminum cans and plastic soda bottles have become thinner over the years, but more reductions will require a whole new kind of manufacturing process.

• 这方面已经有了一些进展--几年来，铝制罐和塑料汽水瓶变得越来越薄了，但要进一步减轻重量，就必须使用全新的制造过程。