What is the verb in sentence kolkata a big city?

The sentence "Kolkata a big city" is grammatically incorrect. It lacks a verb to connect the subject "Kolkata" with the predicate "a big city."

To make it a complete sentence, you need to add a verb. For example:

* Kolkata is a big city. (The verb is "is")

* Kolkata remains a big city. (The verb is "remains")

* Kolkata has become a big city. (The verb is "has become")