Read the introduction of Deep in the Jungle: Just then, the jaguar vaulted from the tree, with its massive paws spread out toward me. I had nowhere to run. Enclosing me on three sides were walls of rock. To my left, a steep granite cliff sliced through the dense forest down to the ferocious white water. I had to escape somehow. Sweat beaded on my forehead and dripped into my eyes. I had to make a split-second decision or risk becoming entangled in the jaguar's grasp.

How does the author show the reader that the main character is feeling nervous?