open-mouthed

The uncivilized guest chewed with his mouth open.

举止粗鲁客人张着嘴巴咀嚼着。

Open your mouth wide.

张大你嘴。

He opened his mouth to make a caustic retort.

他张嘴开始进行刻薄反击。

She opened her mouth to receive the papery-thin wafer.

她张开嘴领受薄薄圣饼。

Gawp (at) means to look at someone or something in a foolish way with the mouth open.

指傻头傻脑地张着嘴看某人或某物。

The minute the door opened, I felt too stunned to open my mouth, staring at her scorched and toilworn face under the glaring lamp, as if an ancient thread-bound book.

灯光下，她枯黄憔悴如同一册古老线装书。