Correct

绵长

/ miáncháng / 
Strokes

Definition

long and continuous (coastline, sound etc)/extensive/prolonged

Example

As an Adjective

(of time) very long

1
Fúshòu
福寿
miáncháng
绵长
  
。

I wish you a happy and long life.

2
Suìyuè
岁月
miáncháng
绵长

long period of years