- 1aC1
/ˈduːəl/ · /ˈdjuːəl/
Having two parts, or made to do two things at the same time.
雙重的
核心畫面
Picture one thing carrying two of something at once — two parts, two roles, or two uses packed into a single body, like a driving-school car with a full set of controls on both the student's and the instructor's side.
可以想成一個東西身上同時裝了兩套：兩個部分、兩種身分、或兩種用途擠進同一個載體裡。像一輛駕訓車，學員座和教練座各有一…更多收起
可以想成一個東西身上同時裝了兩套：兩個部分、兩種身分、或兩種用途擠進同一個載體裡。像一輛駕訓車，學員座和教練座各有一副方向盤和煞車——同一台車，卻能兩邊各自操作。原始詞典資料12 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
dualadj/ˈd͡ʒuː.əl/
- 1
Characterized by having two (usually equivalent) components.
- a dual-motor vehicle
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Pertaining to two, pertaining to a pair of.
- dual engine failure
- dual citizenship
- 3
grammarhuman-scienceslinguisticsPertaining to a grammatical number in certain languages that refers to two of something, such as a pair of shoes.
- Modern Arabic displays a dual number, as did Homeric Greek.
- 4
mathematicsnatural-sciencesphysical-sciencesExhibiting duality.
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linear-algebramathematicssciencesBeing the space of all linear functionals of (some other space).
- Accordingly, a hyperplane in the sample space is dual to a subspace in the variable space.
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category-theorycomputingengineeringBeing the dual of some other category; containing the same objects but with source and target reversed for all morphisms.
- Every category is dual to its own dual, so if a statement holds in all categories so does its dual.
dualnoun/ˈd͡ʒuː.əl/
- 1
Of an item that is one of a pair, the other item in the pair.
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geometrymathematicssciencesOf a regular polyhedron with V vertices and F faces, the regular polyhedron having F vertices and V faces.
- The octahedron is the dual of the cube. The icosahedron is the dual of the dodecahedron.
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grammarhuman-scienceslinguisticsThe dual number.
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mathematicssciencesOf a vector in an inner product space, the linear functional corresponding to taking the inner product with that vector. The set of all duals is a vector space called the dual space.
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governmenthobbieslifestyleA head-to-head match or meet between two teams, such as two high schools or colleges.
- Wrestling duals and meets take place at the Wisconsin Field House. There are no advance single event ticket sales.
- But Dave agreed to participate in the Bulgarian dual, and that trapped me into having to wrestle, too.
dualverb/ˈd͡ʒuː.əl/
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To convert from single to dual; specifically, to convert a single-carriageway road to a dual carriageway.
- I have to declare an interest and I do so with some ambivalence because if the road is dualled it is likely to take half of my front garden.
- The power generation and propulsion systems are dualled to accommodate component failure and maintain propulsion at reduced speed should any part of one system be lost.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。