这块塑料板太硬，完全无法弯曲。

This plastic board is completely ___inflexible and cannot bend at all.

老板对工作时间表的态度非常固执，拒绝做任何调整。

The boss is ___inflexible about the work schedule and refuses to make any adjustments.

学校的考试时间表是固定的，不能随意更改。

The school's exam schedule is ___inflexible and cannot be changed easily.