children start ( ) their clothing styles change 变形填空- -

填changing.
关于start doing 和start to do 的区别,可以到参见xiaowu191网友的回答：
1) 谈及一项长期活动或开始一种习惯时,使用doing.
How old were you when you first started playing the piano?
你几岁时开始弹钢琴?
2) begin, start用进行时时,后面动词用不定式to do
I was beginning to get angry.
我开始生起气来.
3) 在attempt, intend, begin, start 后接know, understand, realize这类动词时,常用不定式to do.
I begin to understand the truth.
我开始明白真相.
4) 物作主语时
It began to melt.

changing

start doing sth. 开始做某事

to change /changing

with

Children start (changing ) their clothing styles.
start doing sth. "开始做某事" 固定搭配

start changing