English grammar – Spot the error (choose the part with an error or “No error”). Sentence: He ought / not have / done such a / filthy thing.

Introduction / Context:
The item tests the correct construction with the modal “ought to.” The sentence is split into four parts; pick the incorrect fragment.

Given Data / Assumptions:

• “Ought to” must be followed by a bare infinitive.
• In perfect infinitive constructions, use “ought not to have + past participle.”

Concept / Approach:
The fragment “not have” is missing “to.” The correct negative is “ought not to have done …”.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

Common Pitfalls:

Final Answer:
not have