It is very difficult the little boy carry the big box.A. of; forB. to; toC. for; toD. by;

问题补充：

It is very difficult the little boy carry the big box.

A. of; for

B. to; to

C. for; to

D. by; for

答案：

A. of; for

B. to; to

(答案→)C. for; to

D. by; for

解析：固定句式It’s adj for sb to do sth做某事对某人来说怎么样。本句中it是形式主语，真正主语是to do sth，for后面是动作对象。句意：运这个大箱子对于这个小男孩来说太难了。故选C。