“张口惊视的”可以翻译为 “with a gaping, astonished look” 或者 “staring open-mouthed in astonishment” 。
“with a gaping, astonished look” 直接描述了人张着嘴、一脸惊讶的神情状态;“staring open-mouthed in astonishment” 同样生动地体现出张着嘴、因惊讶而凝视的样子。