Robert is said ______ abroad ,but I don’t know what country he studying in .A .to have studied B .to study C .to be studying D .to have been studying选择哪个啊?been 怎么使用?

问题描述:

Robert is said ______ abroad ,but I don’t know what country he studying in .
A .to have studied B .to study C .to be studying D .to have been studying
选择哪个啊?
been 怎么使用?