Answer:
Step-by-step explanation:
Her stomach dropped like a free falling elevator. [This is a Simile] She was so nervous that her stomach seemed to be reaching for new lows.
Her voice an imposter as it boomed through the microphone. [Metonymy]
Her voice sounded totally unfamiliar to her. It was an imposter imitating her real voice.
You get the idea that she didn't want to give a speech in front of this crowd.