It is very kind you to help me with my lessons because it is very difficult me to learn them well.
A. of； for
B. of； of
C. for；of
D. for； for
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(答案→)A. of； for
B. of； of
C. for；of
D. for； for
解析：考查句型：It is +形容词+介词+sb to do的用法。形容词为形容人的性格品质的词，应用介词of,形容词为difficult,necessary等词时，应用介词for 。所以选A。