徒步者发现了一个意外的障碍挡住了他们的路。

The hikers found an unexpected ___obstacle blocking their path.

他们必须克服许多障碍才能实现目标。

They had to overcome many ___obstacles to achieve their goal.

语言障碍可能是国际商务中的一个重大障碍。

Language barriers can be a significant ___obstacle in international business.