Most historians believe that the sumerian civilization declined due to a. the drying up of the tigris and euphrates rivers b. constant rebellion within the empire and invasion from outside c. extensive drought and the lack of rainfall over many years d. a devastating plague that killed thousands of sumer's citizens

The organ that has two atria and one ventricle is the

Which revelation resulted from the observation of the spectrum of different galaxies? a. there were more galaxies whose spectrum was blueshifted b. there were no galaxies whose spectrum was redshifted c. there were more galaxies whose spectrum was redshifted d. there were no galaxies whose spectrum was blueshifted

Match the mountains with the type of collision that formed them. a. andes b. aleutians c. north american cordillera d. appalachians 1. continental- continental 2. continental- oceanic 3. oceanic- oceanic 4. arc- continent