He was eating a sandwich hungrily... He had been too excited to eat. He finished the sandwich and, taking a flask from his pocket, he took a short drought. Then he returned the flask to his pocket. He paused for a moment, considering whether he should risk a smoke. It was dangerous. The flash might be seen and there were enemies watching. He decided to take the risk.
This is a simile as it compares two things using the word like. It compares her running across the grass to a cheetah chasing its prey, implying she is running very fast
