It has been raining for three consecutive days.

consecutive 是形容词，由前缀 con-（表示"一起"）和词根 secut（来自拉丁语 sequi，意为"跟随"）加上形容词后缀 -ive 组成，字面意思是"一个接一个跟随的"，引申为"连续的、不间断的"。 consecutive days 指"连续不间断的天数"。