What is a groin vault?
a. a groin vault is a structure that resembles the top half of a sphere.
b. a groin vault comes from the extension of a round arch, similar to a long tube of arches.
c. a groin vault has two barrel vaults of the same diameter which cross or intersect one another.
d. a groin vault has two barrels which extrude into a two dimensional structure.

The coco river is a natural border between nicaragua and which other country

The ozone hole is at its biggest each year in the ? hemisphere in the ? season.

This phrase from the declaration of independence and its primary author thomas jefferson can be used to justify which statement? a) jefferson thought this document could be used in his defense were he put on trial for treason. b) jefferson knew that the colonists' actions would have an international impact. c) jefferson believed that a bill of rights was necessary in the new government. d) jefferson was trying to show the king that the colonists were intellectuals.