英语语法问题the aims of these early grammarians were threefold:(a)

英语语法问题the aims of these early grammarians were threefold:(a) they wanted to
the aims of these early grammarians were threefold:(a) they wanted to codify the principles of their languages,to show thatthere was a system beneath the apparent chaos of usage.
这个句子中的to…to是两两个并列的句子的吗?可以用,来分两个并列句?
To show that 是一个宾语从句吗?是不是that可以省略?