a border between two countries , or ( especially in the past in the United States ) a border between land used to grow crops where people live and wild land
发音
例句
1. The frontier station was starved for food and water. 边防站急需食物和水。 2. Areas near the frontier were rough and lawless in the old days. 过去边远地区混乱不堪,而且没有法律。