12. Which of these characteristics contributed the most to vertebrate success in
relatively dry environments?
(A) the ability to maintain a constant body temperature
(B) the shelled, amniotic egg
(C) two pairs of appendages
(D) four-chambered heart
(E) greater speed of locomotion
答案:登入後查看
統計: 尚無統計資料
統計: 尚無統計資料