Stepped out ten feet and then put a mark in the ground.
量出10英尺；然后在地上做个记号。
Smith ground out his three novels a year for over30 years.
史密斯每年涂写出三部小说，30多年来，年年如此。
In digital signal technique, a signal that uses a positive(or negative) excursion and ground as the two binary signal states.
在数字信号技术中，用正（或负）向电压与地两个电平来表示二进制“1”和“0”的一种信号
