Isn't it very kind __________ your parents to do that for us?
for B to C. about D. of
Isn't it very kind __________ your parents to do that for us?
for B to C. about D. of
D
本题是固定用法的考查。It is+形容词+of／for+sb．+to do是固定的句型。但两个句型用法不同，如果形容词表示人的性质，如kind，nice等必须用of。