问题补充：
We all think is kind you to give your seat to a young lady with a baby in her arms yesterday.
A. that, for
B. it, for
C. it, of
D. that, of
答案：
A. that, for
B. it, for
(答案→)C. it, of
D. that, of
解析：根据句式结构可知，本句是一个固定句型：It is +adj.+for/of sb. to do sth.it在此处做形式主语，没有意思；若形容词是描述不定式行为者的性格、品质的，如kind，good，nice，right，wrong，clever，careless，polite，foolish等，用of sb。所以本题选C。
