aswellas相联2个不定式动词,后面的要去掉to必须如此?请看下面例句为何如此Thecompaniesbuildingthecanalstotransportcoalneededsurveyorstohelpthemfindthecoaldepositsworthminingaswellastodeterminethebes

Question

as well as 相联2个不定式动词,后面的要去掉to 必须如此?请看下面例句为何如此
The companies building the canals to transport coal needed surveyors to help them find the coal deposits worth mining as well as to determine the best courses for the canals.
他工作的那家公司致力于开掘一条运河来运输煤矿,需要测量员帮助他们探寻值得挖掘的煤矿所在地,并为他们决定最佳的运河路线.
主语：companies
谓语：needed
宾语：surveyors
宾补：to help them find the coal deposits worth mining as well as to determine the best courses for the canals.
有点不清楚：就是这个小从句中,是用as well as 相联2个动作 to help find 和to determine可语法书上写 as well as 相联2个不定式动词,后面的要去掉to 可本句中没有去掉?
请问：
（1）我上面的句子结构分析错没错
（2）as well as to determine中的to 去不去掉?

Answer 1

当两个不定式比较简单且靠在一起时,去掉更好,更显简洁；
当两个不定式比较复杂,就像例句所示,则不去掉更显得结构明晰.
连词and, or, but, as well as等引导的两个不定式,后面的不定式加to不加to都可以.