问题补充：
To master a foreign language,.
A. a lot of practice is needed
B. it needs a lot of practice
C. practice is in need of
D. one needs a lot of practice
答案：
A. a lot of practice is needed
B. it needs a lot of practice
C. practice is in need of
(答案→)D. one needs a lot of practice
解析：不定式常修饰动词状语，表示行为的目的、结果、原因等。for+动名词一般不做目的状语，但for+名词化了的动名词可作原因状语
