Complex sentence: Traumatized by her encounter with the Alien, Ripley initially refuses, but relents after experiencing recurring nightmares about the creature; she makes Burke promise to destroy, and not capture, the Aliens.
Split into simpler sentences: Traumatized by her encounter with the Alien, Ripley initially refuses, but relents after experiencing recurring nightmares about the creature. She makes Burke promise to destroy, and not capture, the Aliens.