Grammar - Is this type of sentence structure correct [duplicate]
Solution 1:
The finite verb "is" is many times ellided (though not necessarily) in such constructs:
Active Grammar Level 3 Without Answers and CD-ROM - Page 99 Mark Lloyd, Jeremy Day - 2011
9 We use two comparatives with the, if one change causes another.
The higher the number of trips made by its staff', the greater its 'carbon footprint'.
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English for Academic Research: Grammar Exercises By Adrian Wallwork