Final answer:
The sentence 'Digging became an impossibility for him' is correct, as it does not contain a predicate-subject mismatch. The predicate describing 'digging' aligns with the subject, ensuring clarity and correctness in the sentence structure.
Step-by-step explanation:
The question at hand asks whether the sentence "Digging became an impossibility for him" contains a predicate-subject mismatch. In this sentence, the subject is the act of 'digging' and the predicate relates to it being 'an impossibility for him'. The sentence is correct as the predicate agrees with the subject; there is no mismatch because 'digging' is accurately described as having become an impossibility. It is neither incorrect, ambiguous, nor redundant. Understanding the relationship between subjects and predicates can reduce ambiguity and increase the clarity of language used.
If there is difficulty in establishing the validity of a sentence, as suggested in an additional point of reference, it might be due to issues in the construction of the sentence, such as a predicate-subject mismatch. However, in this case, there is no such confusion, thus no need for revising the topic sentence.