A decision should be made as to whether further action ought be taken. 點解 ought 後的 to可被省去?

"Ought to" is a phrasal modal verb. It is used with the base form of a verb. The negative form of "ought to" is "ought not to," which is sometimes shortened to "oughtn't to" in spoken negative.
引用自 p.1091 Collins Cobuild English Dictionary for Advanced Learners third edition

因為ought to是一個「片語助動詞」，我們不能將to省去，後面的「主要動詞」用「原形動詞」。ought不能單獨使用，它的結構關係不是 ought + 不定詞；而是 ought to ＋原形動詞。

... ought to be taken.才是正確的寫法。

A decision should be made as to whether further action ought be taken. 華文譯：一個應該(被)做的決定 ─ 關於是否更進一步的行動應該被採取。
“(should) be made”：(助動詞+)「原形動詞+過去分詞」=表「現在式+被動語態」，而“ought be taken”：(助動詞+)「原形動詞+過去分詞」=表「現在式+被動語態」，兩者符合「時態一致」原則。
“ought” 係助動詞，通例伴著”to V (不定詞)”。惟「助動詞」文法基本上係修飾(伴著)「原形動詞」，而本題目的『行動』使用「被動語態」為宜，所以用“ought be taken”，而不用“ought to take”。
●一、“ought to”是一個「片語助動詞」，不能將”to”省去。但是“ought”並非“ought to”省去“ to”而來的。
●二、”... ought to be taken.”才是正確的寫法？←請問：《be動詞+過去分詞=被動語態》，若是過去式的be動詞 ─ ”... ought to was taken.”是正確的寫法嗎？
●“ought” (美.辭典1) modal verb =【語】情態(助)動詞 // “ought” (美.辭典2) aux.v.(助動詞) // “ought”查無此字， “ought to” (美.辭典3) modal verb(情態(助)動詞) // “ought” (美.辭典4) auxiliary verb(助動詞) // “ought” (日.辭典1) [助動詞] ((通例 to つき不定詞を伴う；ought to … // “ought” (日.辭典2) [助動詞] […《【用法】 常に to do を伴い，過去の行動について述べる時には完了形不定詞を伴う》// “ought” (華文.辭典1) aux.助動詞 // “ought” (華文.辭典2) aux.助動詞

A decision should be made
as to whether
further action
ought be taken:-
Error&correction:-
(1)ought (aux.v) + root v (to v---ori v...the .infinitive )
eg:-You ought to be more decisive/decided re:.Q1.

(2)(should) be + taken (pp) meaning passive mood----->referring action only.....
(2a)(ought) be + taken(pp) meaning is (to v + pp= present tense =passive voice)=sequence referring Okay.
---eg:You ought be taken by action. re:-Q2
The Ellipsis means omission from a sentence of words needed to complete the construction of the meaning when instance if this ---ought----is shown in your Exam.question.Okay ?

IDK

A decision should be made as to whether further action ought be taken. 點解 ought 後的 to可被省去?

A decision should be made as to whether further action ought be taken.
關於應當作出的決定, 採取進一步行動是必須的

☆ 1. ought是助動詞後➕root verb原動詞 2. be ➕taken（過去分詞)已經是"被動語態"

另例: You ought to be more careful.
你應該小心一點.

He ought be at home by this time.
這個時間他應該在家裡。



謹 供參考, 謝謝！🤔

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"Ought to" is a phrasal modal verb. It is used with the base form of a verb. The negative form of "ought to" is "ought not to," which is sometimes shortened to "oughtn't to" in spoken negative.
引用自 p.1091 Collins Cobuild English Dictionary for Advanced Learners third edition

因為ought to是一個「片語助動詞」，我們不能將to省去，後面的「主要動詞」用「原形動詞」。ought不能單獨使用，它的結構關係不是 ought + 不定詞；而是 ought to ＋原形動詞。

... ought to be taken.才是正確的寫法。