道理站得住腳
把檢查的對象從票換成想法：一個理由被別人翻來看的時候撐得住、挑不出破綻，就跟票過關一樣。
well-founded, sound · adjective · B2
A reason, argument, or point that is valid is sensible and based on good sense, so other people accept it as fair.
站得住腳的
核心畫面
Picture handing your ticket to the person at the gate. They look at it, and it holds up — the date is right, the stamp is there — so you go through. Valid is that moment of holding up under a check. A reason can hold up when people examine it in exactly the same way a ticket holds up at the gate.
可以想成你把票交給門口的人。他看了一眼，票撐得住——日期對、章也蓋了，你就進去了。valid 就像「被檢查的時候撐得…更多收起
可以想成你把票交給門口的人。他看了一眼，票撐得住——日期對、章也蓋了，你就進去了。valid 就像「被檢查的時候撐得住」那一刻。一個理由被別人拿來檢視時站得住腳，跟一張票在門口過得了關，是同一個畫面。From the word’s history
Valid came through French from Latin validus, 'strong, effective, powerful', from valere 'be strong'. That old strength is still doing the work: a valid ticket and a valid argument are both strong enough to survive being checked.
valid 經由法文來自拉丁文 validus「強壯的、有效的、有力的」，字根 valere 就是「有力量」。那個「強」到今天還在做事：valid 的票和 valid 的理由，都是被人拿去檢查時撐得住的東西。
Online Etymology Dictionary — etymonline.com/word/valid
From the picture
Also in this word
officially acceptable · adjective · B2
A ticket, document, or card that is valid is officially or legally accepted, so you can use it.
有效的
accepted by a computer system · adjective · B2
A valid password, ID, or code is one that a computer system will accept as correct.
有效的
原始詞典資料6 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。
validadj/ˈvælɪd/
- 1
Well-grounded or justifiable, pertinent.
- I will believe him as soon as he offers a valid answer.
- Few concepts are as emotionally charged as that of race. The word conjures up a mixture of associations—culture, ethnicity, genetics, subjugation, exclusion and persecution. But is the tragic history of efforts to define groups of people by race really a matter of the misuse of science, the abuse of a valid biological concept?
- 2
Acceptable, proper or correct; in accordance with the rules.
- A valid format for the date is DD/MM/YY.
- Do not drive without a valid license.
- 3
Related to the current topic, or presented within context, relevant.
- 4
human-scienceslogicmathematicsOf a formula or system: such that it evaluates to true regardless of the input values.
- 5
human-scienceslogicmathematicsOf an argument: whose conclusion is always true whenever its premises are true.
- An argument is valid if and only if the set consisting of both (1) all of its premises and (2) the contradictory of its conclusion is inconsistent.
- 6
ChristianitylifestylereligionGenuine - as distinguished from efficient or regular - sacrament.
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。