The girl went to have piano lessons at the training center with her sistershe would stay f

问题补充：

The girl went to have piano lessons at the training center with her sistershe would stay for an hour.

A. who

B. where

C. which

D. what

答案：

A. who

(答案→)B. where

C. which

D. what

解析：考查定语从句。定语从句Where she would stay for an hour修饰表示地点的先行词the training center。因为这个定语从句很完整，所以使用关系副词where。