comparative!! the bigger the ...

I have found the following 4 senteces in an exercise book.

1). The bigger a car is, the more expensive it is to run.

2). The older he gets, the more thoughtful he becomes.

3). The worse the weather, the more dangerous it is to drive on the roads.

4). The more complicated the problem, the harder it is to find a solution.

Why there is a verb in the first half of sentence 1) and 2). But in 3) and 4), there are no verbs in the 1st half of them.

According to the book, they are all correct.

Thank you in advance.

Hi Joey,

1). The bigger a car is, the more expensive it is to run.

2). The older he gets, the more thoughtful he becomes.

3). The worse the weather (is), the more dangerous it is to drive on the roads.

4). The more complicated the problem (is), the harder it is to find a solution.

It's just that the verb 'is' is omitted in #3 and #4. You can do this in various situations, eg in #1 as well.

Best wishes, Clive

Hi,

Yes, you need to have the verb as 'be'.

Clive