[General] omiting subject/verb in double comparative structure

[atabitaraf]

Example: The higher the mountain (is), the harder (it is) to climb.
When can we omit the subject or verb in double comparative structures?
Thanks,

 

[bhaisahab]

You can't omit "it is" in the second clause.

 

[atabitaraf]

Thank you,

1. The higher the mountain (is), the harder it is to climb.
3. The better your mark (is), the higher your rank (is).

It hits me that when the verb in the both parts of double comparative is a 'to be' verb we can omit it, am I right? Is the general rule different?

 

[Tdol]

It depends what you're trying to do- you can omit them in speech, but if you omit the verb it will be an incomplete sentence.