Most of the students ________ to the party were from USA.
A.have been invitedB.to be invitedC.being invitedD.invited在线课程D
解析：
通过分析可知本句的主干是Most of the students were from USA,所以此空不是谓语，是一个定语成分。而people与invite之间为“已经发生的被动行为”。