Tom wants to be a singer and he_____. singing lessons to do it.    [ ]

A. took        

B. has taken    

C. is taking    

D. was taking.

关于圆锥肿瘤的叙述不正确的是（）

A.下肢无明显运动障碍

B.常有剧烈神经根痛

C.有马鞍区感觉消失

D.早期即有明显自主神经功能障碍

E.感觉障碍对称分布，多为感觉分离