Both the secretary and the manager _____agreed to attend the meeting.

这是过去完成时,所以是 have + 动词的过去分词
例子
我已经完成作业了
i have finished homework谢谢，但还有不明白的地方。 为什么不是be agreed to的搭配？因为这里不能用被动词， 假如想用 be agreed 的话， 那么meeting 要在前面例子the time of this meeting was agreed upon by both the secretary and the manager.或者This proposal must be agreed to by both parties in order to be valid.嘻嘻， 其实我的英文语法一般般啦。 没有系统学过。对不起， 假如我的解释不够清晰。