presumption of fact (根据已知事实作出的)事实的推定
The presumption is that.... 根据一般的看法,他会参加研讨会
on the presumption that he knew it 假设他是知道那件事的
This was a mere presumption. 这不过是个猜测而已.

a great piece of presumption 非常无礼的举动
He had the presumption to criticize my work. 他竟然评论起我的作品来了.