Answer:
“Putting her sewing aside" is a participial phrase.
Step-by-step explanation:
Participle is the form of verb which is like ‘verb + ing’. In any given sentence, a participle can be either used as adverbs or as adjectives. “Putting her sewing aside” is a participle phrase as the verb form is “put + ing”. It is being used as an ‘adverb’ here as it is describing “how” was the sewing put. Answer is ‘i was put aside’.
Infinitive is a form of verb which looks like ‘to + verb’. So, it is not an infinitive. The italicised portion is not a verb phrase as well.