presumptuous

没有受邀就想坐在主桌，未免太冒昧了。

It was ___presumptuous of her to try seating at the head table without an invitation.

他未经邀请就坐到了主宾的位置上，真是太冒失了。

It was quite ___presumptuous of him to take the guest of honor's seat without being invited.