Only when people have enough to eat and plenty to wear ______ to talk about environmental

 protection. [ ]

A. it makes sense      

B. does it make sense  

C. that it makes sense  

D. do they make sense

鸟翼和鲸类的鳍状肢是（）。

A、同功器官

B、同源器官

C、痕迹器官

D、趋异器官