An animal is a vertebrate. it is warm-blooded and has feathers on its body. which class does it belong to?
a. reptilia
b. aves
c. mammalia

Ecologist have observed a sharp increase of sulfur dioxide in the air . what might be a possible consequence of excessive sulfur dioxide in the air ? a. acid rain b. ozone layer depletion c.ozone layer hole d.increase in sea levels

The distribution of related animals and plants across the world

What form of anesthetic was used for field surgery