解释下这句话的语法结构.And third, I am proposing the construction of a light rail train system, to be built over the next decade, to meet the growing demands of better and more efficient transportation for years to come.首先：逗号后面的to be built是不是扩充完整应该是 which is to be built, 如果不是,请解释.其次,句子最后的for years to come是什么意思,放在句子里做什么成分.最后如果能再把整句翻译一下那就更好了.

解释下这句话的语法结构.
And third, I am proposing the construction of a light rail train system, to be built over the next decade, to meet the growing demands of better and more efficient transportation for years to come.
首先：逗号后面的to be built是不是扩充完整应该是 which is to be built, 如果不是,请解释.
其次,句子最后的for years to come是什么意思,放在句子里做什么成分.
最后如果能再把整句翻译一下那就更好了.