轴线翻身时，保持整个脊椎平直，翻身角度不可超过（）。

A.30°

B.45°

C.60°

D.90°

- How was your trip?      

- Great. It was the most interesting tour __________ I had ever had.       [ ]

A. who        

B. that            

C. where        

D. which