Question

1. Marianne exhibited her model spacecraft at the science fair.

adjective
adverb
conjunction
preposition

I think it's adverb?
Ms. Sue
What do you think is an adverb?

tony
the part of speech of the sentence
Ms. Sue
Sentences are not a part of speech. Only words are parts of speech.

http://www.enchantedlearning.com/grammar/partsofspeech/
tony
okay I reworded it wrong, the function of the sentence
Ms. Sue
The function of this sentence is to make a statement. It's a declarative sentence.

http://www.infoplease.com/cig/grammar-style/sentence-functions-four-tops.html