Final answer:
Mr. Bedford's belief that the Selenites have not let Mr. Cavor live is best illustrated by the passage expressing certainty that no more messages from the moon will be received.
Step-by-step explanation:
The passage from The First Men in the Moon that best illustrates that Mr. Bedford believes the Selenites have not let Mr. Cavor live is: “Whatever it was we shall never, I know, receive another message from the moon.” This sentence conveys a sense of finality and resignation, suggesting that Bedford has no hope of hearing from Cavor again, which implies a belief that Cavor is no longer alive or able to communicate.