As the busiest woman in Norton, she made _______ her duty to look after all the other people’s ..

As the busiest woman in Norton, she made _______ her duty to look after all the other people’s ..

D?

it作形式宾语，真正的宾语是后面的动词不定式短语to look after all the other people’s affairs in that town。注意:只有it能作形式宾语,不能用this, that或one等其他代词。