For example, the Great Barrier Reef in Australia is the largest coral reef system in the world.

VOA: special.2009.04.22

Some form what are called megakaryocytes which become platelets, which are responsible for clotting, for forming a barrier if your circulatory system gets injured so you don't bleed.

还有一些类型的细胞称为巨核细胞,生成有凝血作用的血小板,在你的循环系统受损时形成止血屏障

耶鲁公开课 - 生物医学工程探索课程节选

But with threats, a language barrier and fear of the legal system, victims often do not or are unable to seek help.

VOA: standard.2010.05.24

The fish that,for one reason or another, that found their way past the barrier, we suppressed them and try to take them out of the system to keep them from establishing in Lake Michigan."

VOA: standard.2010.07.20

This part of the Illinois River near Morris is several miles southwest of the electronic fish barrier, a critical point along the Illinois waterway system meant to stop the Asian Carp from reaching Lake Michigan.

VOA: standard.2010.07.19