问题补充：
How very delightful to suggest this!
A. it is you
B. it was for you
C. it is of you
D. it was you
答案：
A. it is you
B. it was for you
(答案→)C. it is of you
D. it was you
解析：这是感叹句,it为形式主语, of you to 为不定式的复合结构做真正的主语,因为 delightful是you的逻辑上的表语,所以不用介词for而用of引起这不定式复合结构.
