I believe in this sentence:

It was the world’s first movie studio.

the subject is: movie studio
the predicate is: was

Am I correct?

You have the simple predicate correct.

But "movie studio" is the predicate nominative, not the subject.

Ask "what was?" to find the subject.

Right. "It" is the subject.

Yes, you are correct! In the sentence "It was the world's first movie studio," the subject is "movie studio," and the predicate is "was."

To identify the subject and predicate in a sentence, you can follow these steps:

1. Determine what or who the sentence is talking about. This is the subject. In this case, the subject is "movie studio." Note that the subject can sometimes be a pronoun, like "it" in this sentence.

2. Find the verb or verb phrase in the sentence. This is the predicate. The predicate describes the action or state of being of the subject. In this case, the verb is "was," which is a form of the verb "to be."

By analyzing the sentence, you correctly identified the subject as "movie studio" and the predicate as "was." Well done!