Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

Reptiles are heterothermic, .e., they do
not their body temperature.
however are the
homeothermic animals, they able to
maintain body temperature
constant.

are many birds live in intense
regions. Penguins are of
birds that in polar region.