In the a. d. 600s, north africa was conquered by. a. the egyptians b. arab muslims c. europeans d. africans from south of the sahara

In north america, most winter storms form when cold, dry air from interacts with warm, moist air from

The impact of a large asteroid comet with earth has been proposed to have caused the extinction of the dinosaurs. the impact site of this comet is in or near

Plants in the tundra biomes have had to adapt to live long periods of time without a. cool temperatures b. sunlight c. oxygen d. water