The teacher made her duty to care for the lives and study of her students.A. one B. that C

问题补充：

The teacher made her duty to care for the lives and study of her students.

A. one

B. that

C. it

D. this

答案：

A. one

B. that

(答案→)C. it

D. this

解析： 考查代词it作形式宾语，真正的宾语是后面的不定式，make it a duty使成为职责，句意：老师使关心学生们的生活和学习成为了她的职责。故选C。