It is very difficult ______ some tourists to understand differen

It is very difficult ______ some tourists to understand different cultures.
A、of
B、with
C、for
D、to
【正确答案】：C
【题目解析】：C. for - 当使用“It is + 形容词 + for sb. to do sth.”的结构时，形容词描述的是“to do sth.”这个行为的难易程度。在这个句子中，“difficult”正是用来描述“for some tourists to understand different cultures”这个行为的难易程度，因此“for”是正确的选择。