Why is it believed that large parts of the United States were once covered by shallow seas?
What will be an ideal response?
Answer: Marine fossils found in the interior of the continent.
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How is a technical civilization defined?
A) a civilization that can avoid self-destruction for long periods B) a civilization that can communicate over interstellar distances C) a civilization that has the ability to store and process information D) a civilization that has developed interplanetary space travel E) a civilization that can construct tools out of raw materials
A unified model of active galaxy cores can explain different types of Seyfert galaxies, quasars and other active galaxy types by differences in the ____
a. mass of the supermassive black hole b. size and thickness of the accretion disk c. magnetic flux strength in the jets d. amount of dust in the accretion disk e. tilt of the accretion disk to the line of sight
Why can infrared telescopes operate from high flying aircraft and high mountain tops whereas X-ray telescopes must be placed in orbit?
What will be an ideal response?
What two vectors are each the same magnitude as and perpendicular to 
?
What will be an ideal response?