OF THE ANIMALS WITH BACKBONES, THE FIRST TO APPEAR WEREA. MAMMALS...

61. - 2 DE THI THU DAI HOC CAO DANG NAM HOC 20092010 MONTHI TIENG ANH VA DAP AN SO 34
Tiếng Anh 2 DE THI THU DAI HOC CAO DANG NAM HOC 20092010 MONTHI TIENG ANH VA DAP AN SO 34

61. Of the animals with backbones, the first to appear were

A. mammals

B. fish

C. amphibians

D. birds