To 부정사의 의미상의 주어

예시)

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It's easy for me to read this book 

It is difficult for him to finish the work in a week 

It is not safe for the kids to play on the street 

Of--------------------------------------------------

It was wise of you to refuse his offer 

It is very cruel of him to do such a thing. 

It was careless of her to break the dishes 

It's foolish of him to say such a thing.