[請益] 該句while的用法

[b930300 (rgw)]

句子: He became anamored with the field while at LaRabida Children's Hopital
      in Chicago, caring for patients with cerebral palsy.

疑問:

我想這邊的 caring 應該不是分詞構句吧!?
是while後面省略主詞的原因吧?! at LaRabida Children's Hopital
      in Chicago那後面有需要逗號嗎?

謝謝

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◆ From: 210.69.13.1
→ yangivy:caring看起來是分詞構句
→ yangivy:He became enamored with the field while (he was) at
→ yangivy:LaRabida Children's Hopital in Chicago, and he cared
→ yangivy:for patients with cerebral palsy.
→ yangivy:分詞構句要用逗號隔開沒錯
→ priv:就算是 while 省略主詞的情形在文法上也算是分詞構句
→ priv:稱為「保留連接詞」
→ priv:至於此句原本的結構如樓上所述