1 He was dumbfounded by the allegations.
2 She was completely dumbfounded by the news.
3 We were completely dumbfounded by her rudeness.
4 He was completely dumbfounded by the incident.
5 This suggestion dumbfounded Joe.
6 I stood there dumbfounded.
7 I've seen more than a few hives throwing off a swarm, and never has one failed to transfix me utterly, or to dumbfound everyone else within sight of it.