问题
选择题
Robert is said abroad, but I don’t know in which country he is.
A．have been studying
B．to have been studying
C．have studied
D．to have studied
答案
答案：B
be said后应该接不定式形式，而且根据I don’t know in which country he is 意味着他现在仍然在国外学习，表示从过去到现在一直在做某事，要用完成进行体。所以选B，不能选D.