“boundary marker”造句，怎麼用boundary marker造句

2、A similar pin forming a projection that may be used as a support or boundary marker.

1、Studies in bounds of undecided boundary of River Uda and boundary marker in Sino-Russian Treaty of Nerchinsk;

3、The boundary marker stands on a stone ridge, like a solid sentry, gazing at the mountains and rivers along the border between China and Vietnam.