Separate the complete subject and the complete predicate.
There are many theories/ about the Tunguska Fireball.
Is this right?
Nope. Since this sentence is inverted, it's tough.
The complete subject is many theories about the Tunguska Fireball.
The complete predicate is there are.
Is this one right.
The most likely theory, perhaps,/called it a comet of tiny pieces of metal.
It's right, except that "perhaps" is an adverb, modifying the verb, "called."
The most likely theory, | perhaps, called it a comet of tiny pieces of metal.
Thank you
You're welcome.
Yes, that is correct. In the sentence, "There are many theories about the Tunguska Fireball," the subject is "there" and the predicate is "are many theories about the Tunguska Fireball." To separate the complete subject and complete predicate, you would write it as:
Complete subject: There
Complete predicate: are many theories about the Tunguska Fireball