Gerund as object: "handling complaints" in "training staff in handling complaints" serves as a gerund phrase, used as an object, adding complexity and precision to the sentence.
Infinitive structure: "to listen actively, empathize, and respond effectively" uses an infinitive structure to list the skills that employees need to learn, demonstrating clear goals and structure.
Present participle phrase as adverb: "preparing them for real-life situations" in "preparing them" functions as a present participle phrase, used as an adverb, showing the training purpose, while also increasing the coherence and complexity of the sentence.