Is is the third-person singular of to be

It's not all right for you to cover for your sick-ass, twisted son, just because he's yours and let him tear apart a woman and her family.

The Equator, as everyone knows, is an imaginary line or circle girdling the Earth half-way between the North and South poles.

In Lexington, which was just then establishing itself as the principal town in Kentucky, he found work quarrying stone for a tavern keeper. Once again, the wages were low, and his employer strove by every means in his power to take advantage of me.