growing VS grown
Please read this: In the 1960s, Korea experienced rapid industrialization. Although this meant that the economy developed at an incredible rate, it also intensified the gap between the haves and the have-nots. The laborers were forced to work for low pay, with long hours, under poor working conditions. Eventually, their grown complaints were expressed through many events.
At the last sentence, why should "grown" be changed to "growing"? I don't really understand this. Please help me!