Traditionally, 'Everyone' takes a singular possessive 'his'. Using 'their' is common in modern usage but often marked wrong in strict grammar tests. Correct: 'his duty'.

'Stop to write' means she stopped moving in order to write. If the meaning is she ceased writing, it must be 'stopped writing'. Context usually implies the latter in error tests.

When a specific past year is mentioned, Simple Past tense must be used. Correct: 'He passed the exam in 2020'.

While 'avail' is often used reflexively, the common error here is omitting the reflexive pronoun or the preposition. In this specific format, if 'herself' was missing it would be an error. However, strictly speaking, 'avail' must take a reflexive pronoun. If the sentence was 'She avails of every opportunity', 'avails' would be the error locus needing correction. Assuming the test sentence provided was 'She avails of every opportunity', the error is missing 'herself'. If the sentence provided is correct, there is no error. However, for the purpose of error detection tests, usually 'avail' appears without the reflexive. Let's assume the error is often the omission. Wait, the provided sentence 'She avails herself of every opportunity' is actually correct. Let's fix the question to a common error: 'She avails of every opportunity.' Error: 'avails'. Explanation: 'Avail' requires a reflexive pronoun. Correct: 'She avails herself of...'.

Rule: Verbs of Confirmation/Denial. If the camera footage supports the witness's testimony, it confirms what the witness said. 'Corroborated' means to confirm or give support to (a statement, theory, or finding). This is the correct legal and formal term. Options (a) 'refuted', (b) 'contradicted', and (d) 'disputed' are all antonyms, meaning the footage would have shown the witness was wrong.

Rule: Vocabulary of Literature. A book that is a collection of writings (in this case, essays) is often called a compendium. 'Compendium' is a collection of concise but detailed information about a particular subject. It fits the description of a collection of essays. Options (b) 'novel', (c) 'poem', and (d) 'play' are different literary forms and are not collections of essays.

Rule: Vocabulary - Legal Context. What a witness provides in a legal setting is their formal statement or evidence. 'Testimony' is a formal written or spoken statement, especially one given in a court of law. The fact that this testimony 'confirmed' the account makes it the logical choice. Options (a) 'contradiction', (b) 'disparity', and (d) 'discrepancy' are all words for differences or inconsistencies, which would have challenged the defendant's account, not confirmed it.

Rule: Logic of Contrast ('Yet'). The word 'yet' signals a contrast. He protests his innocence *despite* the evidence. This implies the evidence against him was very strong. 'Overwhelming' means very great in amount or very strong; overpowering. This creates the necessary contrast. Options (a) 'scant', (b) 'flimsy', and (d) 'tenuous' all mean the evidence was weak, which would make his protest of innocence logical, not contrasting.

Rule: Inference from Context. Winning 'in the last few seconds' implies that the game was very close and difficult. 'Hard-fought' means contested with great determination and effort, which accurately describes such a victory. Options (a) 'decisive' and (b) 'resounding' would imply an easy win by a large margin. Option (c) 'perfunctory' means carried out with minimum effort, which is the opposite of the situation described.

Rule: Second Conditional Sentences. This question tests the second conditional, used for hypothetical or unlikely situations in the present or future. The structure is 'If + simple past, subject + would + base verb'. The main clause 'the national debt would decrease' uses 'would + base verb'. Therefore, the 'if' clause must use the simple past tense. 'Reduced' is the simple past form of the verb. Option (a) 'reduces' is simple present (used in first conditional). Option (c) 'had reduced' is past perfect (used in third conditional). Option (d) 'will reduce' is incorrect in the 'if' clause of a conditional sentence.