mary an American friend ___ looking forwatd to visiting china at present.
问题描述：
mary an American friend ___ looking forwatd to visiting china at present.
A.are B.is C.were D.have been 为什么?
答
B
因为是单数
请及时采纳,多谢!哪里能说明是单数呢？mary an American friend 中的 friend ，而不是friends，是单数。