6. The first vertebrates appeared during a. Precambrian time
b. the Paleozoic Era
C. the Mesozoic Era
d. The Cenozoic Era

double the distance = divide strength by 4

no sign of dia of fuel cell

the five characteristics of adolescence are biological growth and development, and undefined status, increased decision making, increased pressure and the search of self.

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.