77.The professor was delighted to find that two thirds of the project ___by the students independently.(finish)
教授高兴地发现学生们已独立完成了该项目三分之二的工作
had (already) been finished
根据以上解题思路可知学生已经独立完成了工作之后教授才发现，所以应该用过去完成时had (already) been finished。
根据句意可知，finish动作发生在was delighted to find that…之前，故用过去完成时，表示“过去的过去”，且与project构成逻辑上的动宾关系。因此答案为：had (already) been finished。
对于过去完成时用法掌握不全。