common frontier的用法和樣例：
例句
- There is no common boundary at which the syllables join, but each is separate and distinct from the rest.
音節之間沒有結合的共同邊界，而且每一音節都和其它音節是分離的和截然不同的。 - The two tremendous continental countries shared a frontier of 4,000 miles in a vast arc from the frozen tundras of Siberia to the stark deserts of Central Asia.
這兩個遼闊的大陸國家的共同邊界從西伯利亞凍土地帶到中亞細亞荒漠劃出一個大弧形，長達四千多英里。
