Final answer:
The correct way to rewrite the sentence fragment is: Last night, or this morning truly, I was up on the housetop.
Step-by-step explanation:
The correct way to rewrite the sentence fragment is: Last night, or this morning truly, I was up on the housetop. By adding the subject 'I', the sentence becomes grammatically complete. The adverbial phrase 'last night' can either be placed at the beginning or the end of the sentence, while the phrase 'this morning truly' can only be placed in the middle.
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