I think is necessary my 20-year-old daughter to have her own mobile.A. that; ofB. it; ofC

问题补充：

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

答案：

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。