All mammals have hair, but not always evid
题型：单项选择题
问题：
All mammals have hair, but not always evident.()
A. but it is not
B. but it is
C. but they are not
D. but they are
All mammals have hair, but not always evident.()
A. but it is not
B. but it is
C. but they are not
D. but they are