高手帮忙改这一个句子的语错误!

高手帮忙改这一个句子的语错误!
However,it is really hard to say that the increasing consumption of petrol is the vital element which underling all of the environment problems.
请说的具体点哦。怎么改。不要改句子，只要改单词.OF我自己也会改
可我觉得WHICH是修饰vital element的，这样的话就不存在逗号的问题了
那把UNDERLING 改成UNDERLIES也是可以的吧
最后一位朋友我不明白你的意思，这句原文的中文：是否不断增加的汽油消耗是导致所有环境问题的最重要因素——这是十分难确定的

这句话错在 which underling.
Which 后面应该跟一个动词,所以应改为：which underlies.
还有一种改法,是直接去掉which,这样变成了：the vital element underling ...把从句变成一个动名词来修饰the vital element.
我的意思是：这句话有两种说法.
1.However,it is really hard to say that the increasing consumption of petrol is the vital element which underies all of the environment problems.
2.However,it is really hard to say that the increasing consumption of petrol is the vital element underling all of the environment problems.
清楚了吗?