As Student Union of university, we should care about the poor children in Western China, save every penny and do what we can to help them, donate our staffs, and write letters and encourage them.
正常来讲,can 后面加do,你问的是“do what we can to help”那句吧?它的结构是“what we can”作从句,实际上是“do sth. to help”,所以can不是跟to do在一起的。
As a number of our Student Union,we should concern about the western needy children in China. We try our best to help them and contribute our staffs,also send letters to inspire them,
最后一句是三个并列【谓语】,都是由同一主语【We】发出的,不是病句。