dual: [17] Dual was borrowed from Latin duālis, a derivative of duo ‘two’ (which is a distant relative of English two). In Latin it was used particularly by grammarians, to denote the category ‘two people or things’ (as opposed to the plural, referring to three or more), and this was the earliest sense of the word adopted by English. (Incidentally, despite its formal similarity, and a common meaning element – two people participate – duel [15] is not etymologically related to dual; it comes from medieval Latin duellum, which was originally an archaic form of Latin bellum ‘war’. => two
dual (adj.)
c. 1600, from Latin dualis, from duo "two" (see two). Related: Dually.
权威例句
1. his dual role as composer and conductor
他兼任作曲家和指挥的双重角色
2. He has dual role as composer and conductor.
他兼作曲家及指挥的双重身分.
3. The airplane had dual controls.
这架飞机有两套操纵装置.
4. The reason for the discount is the use of dual - class shares.
存在折价率问题的原因是双重投票权股票(dual -classshares )的使用.
5. A safety alert system by DTMF ( Dual - tone multifrequency ) mode is introduced.