Dallas: When I give an order, I expect to be obeyed!
Ripley: Even if it's against the law?
Dallas: You're goddamn right!
Context: The captain confronts Ripley after she refused to break quarantine and let an infected crewman back aboard.
Dallas: I haven't seen anything like that except molecular acid. Brett: It must be using it for blood. Parker: It's got a wonderful defense mechanism. You don't dare kill it.
Lambert: You admire it. Ash: I admire its purity. A survivor unclouded by conscience, remorse, or delusions of morality.
You still don't understand what you're dealing with, do you? A perfect organism. Its structural perfection is matched only by its hostility.
I can't lie to you about your chances, but... you have my sympathies.