He has been campaigning on road safety for years - you have to admire his persistence.

persistence 是名词，来自动词 persist（坚持、持续）。persist 由前缀 per-（表示"完全、彻底"）和词根 sist（来自拉丁语，意思是"站立"）组成，字面意思是"完全站立不动"，引申为"坚持不懈"。 persistence 指"坚持不懈、持续不断"的品质或行为。