refractory

这个叛逆的学生拒绝遵守任何课堂纪律。

The ___refractory student refused to follow any classroom rules.

这位患者患有一种对常规药物不产生应答的顽固性癫痫。

The patient suffers from a ___refractory form of epilepsy that does not respond to standard medication.

修理工和一个怎么拧都纹丝不动的顽固螺栓搏斗了半天。

The mechanic wrestled with a ___refractory bolt that would not budge.