He was sustained by the unflagging support of his family.在家人的不懈支持下, 他得以支撑下去。

You wonder how they bear it with such unflagging optimism and acceptance.你会纳闷他们是如何以不变的乐观和忍耐承受这一切的。

The book is not one word too long and its narrative pace is unflagging.这本书文字简练, 叙事流畅。