Difficulty: Easy
Correct Answer: No correction required
Explanation:
Concept/Approach
This is a correct third conditional using inversion in the if-clause: "Had I realised …, I would not have …".
Option analysis
E is correct. A uses a wrong passive; B is the common but incorrect "would have" in the if-clause; C changes meaning/time; D is ungrammatical doubling of "had".
Final Answer
No correction required
Discussion & Comments