He has been working for five days consecutively.

consecutively 是形容词 consecutive 的副词形式，由前缀 con-（表示"一起"）和词根 secut（来自拉丁语 sequi，意为"跟随"）加上后缀 -ive 构成形容词，再加上 -ly 变成副词。consecutively 意思是"连续地、不间断地"。