I think is necessary my 20-year-old daughter to have her own mobile.
A. that; of
B. it; of
C. that; for
D. it; for
网友回答
A. that; of
B. it; of
C. that; for
(答案→)D. it; for
解析：考查固定结构，it is +adj.+for sb to do sth对某人来说做某事怎么样，it是形式主语，真正的主语是不定式to have her own mobile。选D。