解释下这句英文,having discussed怎么就用上了?

问题描述:

解释下这句英文,having discussed怎么就用上了?
the rule about primary school students having evening classes remains to be further discussed.

the rule( about primary school students having evening classes) remains to be further discussed括号里的是修饰rule的. 而having evening classes 是现在分词短语做后置定语,修饰限制前面的primary school ...