To speak hesitantly and in a mumbling or stammering manner, typically due to reservations, shyness, or uncertainty; to hem and haw.
面对突如其来的提问，他一时语塞，嗫嗫嚅嚅地说不出完整的话。
Faced with the sudden question, he was momentarily speechless, mumbling and stammering, unable to form a complete sentence.
Next Idiom