du·al /ˈdjuːəl $ ˈduːəl/ ●○○ adjectiveadj [only before noun] → duelTWOhaving two of something or two parts 双的,双重的,两部分的 → singledual role/purpose/function The bridge has a dual role, carrying both road and rail. 这座桥有双重用途,既作公路又作铁路。
a dual system of education 二元[双元]教育体系
dual citizenship/nationality She has dual nationality, of Canada and Britain (=she is a citizen of Canada and Britain). 她有加拿大和英国双重国籍。
—duality /djuˈæləti $ du-/ noun [uncountableU]