adj.咕哝的；呼噜的
动词grunt的现在分词形式.
I asked him what he thought, but he just grunted. 我问他在想什么，他只哼了一声。
He gave a grunt of approval. 他咕噜了一声表示同意。
He grunted as the bullet hit him. 子弹击中他时他疼得哼了出来。
