路上的一块大石头成了我们前进的障碍。

A big rock on the road became an ___obstacle to our progress.

语言障碍是她出国留学面临的主要困难。

The language barrier was the main ___obstacle she faced when studying abroad.

他的自我怀疑成了追求梦想的最大障碍。

His self-doubt was the biggest ___obstacle to pursuing his dream.