Friends are people who come together to learn and grow with one another, to lighten each other's roads and brightening each other's days.
【正确答案】：Friends are people who come together to learn and grow with one another, to lighten each other's roads and to brighten each other's days.
【题目解析】：后半句中and连接的是to lighten each other's roads和to brighten each other's days，所以形式应该保持一致。