Answer:
Leaning on the rail for support, the novice ice-skater laughed at her own inability to maintain her balance on the ice.
Step-by-step explanation:
A participial phrase is a group of words that consists of a participle and modifiers and/or nouns or pronouns that function as objects that complete the thought.
A participle is a verbal that is used as an adjective. It usually ends in -ing or -ed, which can help you easily recognize it. In the given sentence, the participle is leaning, and the rest of the words that complement it (on the rail for support) represent the rest of the participial phrase.
Just like participles on their own, participial phrases are very similar to verbs but modify nouns, which makes them more like adjectives.