<span>The largest library in the United States, located in Washington, D.C., and maintained largely by federal appropriations. Its original purpose was to provide research facilities for members of Congress; today it serves the public as well.</span>
Tooth
Singular Possessive: Tooth's
Plural Possessive: Teeths'
Puppy
Singular Possessive: Puppy's
Plural Possessive: Puppys'
I'd say the answer is 'the visible is more dangerous than the invisible', because Duncan never suspected that his faithful Macbeth would be the one to kill him.
