speechlessly       
adverb uk/ˈspiːtʃ.ləs.li/ us/ˈspiːtʃ.ləs.li/
 无语地; 哑口无言地
without being able to speak because you are so angry, shocked, surprised, etc. 
  She stared at him speechlessly, hardly daring to believe his words. 她目不转睛地盯着他,几乎不敢相信他的话。 
 I was speechlessly happy. 我高兴得说不出话来。 
 See: speechless
 - More examples
 - Mark could only nod speechlessly.
 - She stared speechlessly at the most money she had ever seen in her life.
 - She nodded speechlessly, then got out of the car and fled into the house.