unflagging
adj. 不屈不挠的；不松弛的，不松懈的
例句
He was sustained by the unflagging support of his family.
他有着来自家庭的持久的支持。
《柯林斯英汉双解大词典》
But market pressures are real and unflagging.
不过市场的压力却是真真切切，无可躲避。
Every time I left her side, I was energized by her courage and unflagging spirit.
每次从母亲身边离开，我都被她勇气不懈的精神所鼓舞着。
