What did harry hess find on the ocean floor that prove the theory of continental drift?

Which of the following can scientists estimate geologic time? a.observing rock sequences b.radiometric dating c.comparing fossils d.all of these

What must happen for new french words to be published in official dictionaries? a. they must be approved by the french academy b. they must be voted on by the people of france c. they must be used by famous french writers d. they must be used by philosophers a. they must be approved by the french academy

Based on what you know about speed of light and sound, which come/comes first in a thunderstorm