问题补充：
The girl spends at least as much time singing as she .
A. studies
B. does studying
C. is studying
D. does to study
答案：
A. studies
(答案→)B. does studying
C. is studying
D. does to study
解析：本题主要考虑1）spend some time doing sth 2）do sth as sb as sb does 故选B
