Why do birds fly? and also how to get rid of scariness of birds?

What does all of the organ system in a human form

Acell in the human nervous system whose primary function is to form myelin and the blood-brain barrier, respond to injury, remove debris, and enhance learning and memory is called a(n) cell.

Drag each label to the correct location in the equation. not all tiles will be used. the density of mercury is 13.6 grams per cubic centimeter. complete the steps for converting 13.6 g/cm3 to kg/m3. (1 kg = 1,000 g, 1 m3 = 106 cm3)