How do mass extinctions differ from background extinctions?

What do animals wth echolocation have in common other than echolocation

This question is only for applicants to scholars for medicine or scholars for dental medicine: what aspects about medicine (or dental medicine) intrigue you? describe how these aspects influence your life. (100-650 words)

Drag each description to the correct location on the image. not all descriptions will be used. describe the parts of a comet. the frozen part of the comet the atmosphere of gases and dust formed when the nucleus vaporizes tail made of small, solid dust particles tail made of ions that appears to point away from the comet's orbit