Shown by surprise, you may be annoyed
Perused with intent, you may regret
Observed on this site, you may verify
Inclined on an airplane, you may have seen
Hint:
Hint
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Sign up to join this communityI think the word all the lines are pointing at is
SPOILER.
Shown by surprise, you may be annoyed
... although I believe research actually shows that people generally enjoy books, movies, etc., more after being "spoiled".
Perused with intent, you may regret
Same meaning as the foregoing.
Observed on this site, you may verify
As for instance in the hint above.
Inclined on an airplane, you may have seen