Final answer:
The sentence suggests that unlike an adjective, which can often be moved within the sentence, the structure involving an adverbial clause must be repositioned or rephrased to maintain sentence coherence. An adverbial clause specifically cannot be exchanged with a noun or an adjective without altering the sentence structure.
Step-by-step explanation:
Unlike an adjective modifier, the sentence cannot be shifted to make sense, but something must be repositioned or rephrased. An adjective modifies or describes nouns, and can often be moved within the sentence while maintaining the overall sense. In contrast, an adverb modifies verbs, adjectives, or other adverbs, often describing time, place, reason, or manner, and is sometimes more fixed in its position within a sentence. Adverbial clauses introduced by words like 'when' provide additional information and cannot equate to nouns or adjectives, thus cannot simply replace one in a sentence without changing the sentence structure.
For example, consider these phrases from your English lessons:
- I need to find an affordable car. ('affordable' is an adjective modifying 'car')
- Pierre quickly ran through the main points of his argument. ('quickly' is an adverb modifying 'ran')
In sentence patterns involving the be verb, a subject is followed by a form of 'be' and then by an adverbial of time or place, an adjectival, or a noun phrase. When this pattern is used, balance in the sentence is critical, and elements cannot be moved haphazardly.