高二英语语法分析It took more than two decades,though,until 1951,for regular colour TV broadcasts to begin in the USA.这里边,For和to都是作什么成分啊?

高二英语语法分析It took more than two decades,though,until 1951,for regular colour TV broadcasts to begin in the USA.这里边,For和to都是作什么成分啊?
高二英语语法分析
It took more than two decades,though,until 1951,for regular colour TV broadcasts to begin in the USA.这里边,For和to都是作什么成分啊?

高二英语语法分析It took more than two decades,though,until 1951,for regular colour TV broadcasts to begin in the USA.这里边,For和to都是作什么成分啊?
这句话可以这样看,把逗号隔开的部分先去掉,It took more than two decades for regular colour TV broadcasts to begin in the USA.
也就是,It took 一些时间 for sth.to do sth.
这样的话,for 和to 的成分就很明显了吧,for是介词,而to是动词不定式.