most of the people-----to the party were famous scientists 为

首先the people 后面应该跟的是定语,在这里做后置定语.
其次the people 在这里是被邀请到Party的.因而应该是being invited.而你想用invited ,不过要变成定语成句了：Most of the people whom were invited to the party were famous scientists.
而to invite 显然不对,你可以多看看语法书.有这方面的知识.