问题补充：
It my mother half an hour to the shopping mall.
A. spends; walking
B. takes; to walk
C. spends; to walk
D. takes; walking
答案：
A. spends; walking
(答案→)B. takes; to walk
C. spends; to walk
D. takes; walking
解析：句意：我妈妈去购物中心需要半个小时。It takes sb some time to do sth.某人花一段时间做某事,固定句型，故选B.
