英语语法关于动名词加S,过去分词,动词ing形式,现在分词类的问题.

英语语法关于动名词加S,过去分词,动词ing形式,现在分词类的问题.
例如下面这篇文章,其在多处有加S和加ed形式的单词,但却不是每处都加,同一个单词有的地方加了有的地方没加,本人英语语法在这方面很薄弱,求醍醐灌顶,另外求推荐一本语法书,不要太冗长,也不要太短,要能在20天左右看完的,求推荐~
The chart gives information about post-school qualifications in terms of the different levels of further education reached by men and women in Australia in 1999.
We can see immediately that there were substantial differences in the proportion of men and women at different levels.
The biggest gender difference is at the lowest post-school level.
Where 90% of those who held a skilled vocational diploma were man,compared with only 10% of woman.
By contrast ,more women held undergraduate diploma(70%) and marginally more women reached bachelor's degree level(55%).
While more women reach undergraduate diploma level than men.
At the high levels of education ,men with postgraduate diplomas clearly outnumbered their female counterparts(70% and 30%,respectively),and also constituted 60% of Master's graduates.
Thus we can see that more men than women hold qualifications at lower and higher levels of education ,while more women reach undergraduate diploma level than men.