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Difficulty: Very hardModal Auxiliaries and Expressing Modality

Read the sentence below and answer the question that follows:

'Given that all entry logs were automatically backed up to a remote server in real time, the suspect ________ modified the transaction details without leaving a detectable digital footprint.'

Which modal auxiliary verb phrase correctly completes the sentence to express past logical impossibility?

  1. could not haveAnswer
  2. B
    might not could have
  3. C
    must not to have
  4. D
    should not had

Answer

The correct phrase is 'could not have' because it accurately expresses a logical deduction of past impossibility given the contextual evidence.
The modal structure 'could not have' correctly conveys a negative logical deduction regarding past events when evidence indicates the action was impossible.

Step-by-Step Solution

1
Analyze the context of the sentence
The sentence establishes that automated real-time backups were present, making untraceable modification logically impossible.
Establishing the logical constraint dictates the specific semantic function required of the modal verb.
2
Select the modal structure for past impossibility
The structure 'could not have + past participle' expresses that an action was impossible in the past.
Modal auxiliaries combined with perfective aspect ('have + past participle') express past deductions.
3
Evaluate the grammatical correctness of distractors
Structures featuring double modals ('might not could have'), incorrect infinitive particles ('must not to have'), or improper past inflections ('should not had') violate modal syntax rules.
Modal auxiliaries must precede bare infinitives and cannot stack directly with other modal verbs.

Key Concept

Expressing past logical impossibility using modal auxiliaries (could not have + past participle)
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Topics

Modal Auxiliaries and Expressing Modality

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