她设法克服了障碍，按时完成了项目。

She managed to overcome the ___obstacle and complete the project on time.

他拒绝谈话是和平的主要障碍。

His refusal to talk is the main ___obstacle to peace.

学生的另一个障碍是图书馆提前关闭。

Another ___obstacle for students is the early closure of the library.