Part 1: 双越比较的语法概念
The 比較級 ... + the 比較級 ... ：越...越...
The sooner, the better.
The cheaper, the better.
The more you eat it, the better you will like it.
= if you eat it more, you will like it better. (副詞比較級 more 修飾 eat, better 修飾 like)
The hotter the water is, the more enjoyable it will be.
= if the water is hotter, it will be more enjoyable.
双“越”比较的主要时态：主将从现
The harder you work, the greater progress you will make.
The higher the unemployment rate is, the more people like you and me will suffer.
不排除：The more he gets, the more he wants.
Or: The harder he tried not to think about her, the more he missed her.
Part 2：比较：双“越”比较在雅思议论文中的加分用法
Example 1: When more machinery is used in modern industry, more workers will get unemployed and the quality of products will get lower.
7分变身： The more machinery is used in modern industry, the more workers will get unemployed and the lower the quality of products will get.
Example 2: 大学招收越多的学生的时候，每个学生所得到的来自教师的关注就会变少同时教学品质也就因此变得更差了。
7分亮句：Some parents believe the more students a university accepts, the less attention every student will get from their professors and thus the worse the quality of tertiary education will become.
Example 3: Environmental Protection
一个城市的私家汽车拥有量和使用率更高的时候，它的空气污染就会变得对人们的健康更加有威胁。
7分神句：The more private cars people own in a city and the more frequently these car owners drive their cars to travel, the more serious the air pollution in this city will become to threaten the physical well-being of all its residents.