英语20.Robert is said _______ abroad,but I don’t know what country he studied in.

问题描述:

英语20.Robert is said _______ abroad,but I don’t know what country he studied in.
20.Robert is said _______ abroad,but I don’t know what country he studied in.
a.to have studied b.to study c.to be studying d.to have been studying
为什么

d