She is said in the United States for four years before she came back to work in our compan

问题补充：

She is said in the United States for four years before she came back to work in our company.

A. to study

B. to be studying

C. to have studied

D. studying

答案：

A. to study

B. to be studying

(答案→)C. to have studied

D. studying

解析：常用句型 sth/sb is said to do ....据说。。。题中出现了for four years 说明要用完成时。