In the sentence, "singing the anthem beautifully, the sanctuary choir touched the emotion of the congregation," singing is used as a(n) and is therefore a(n)
options for blank 1:
adjective
verb
noun
adverb
options for blank 2:
gerund
participle
infinitive

PARTICIPLE

Explanation:

Adding -ing to the base form of a verb creates the present participle. Singing is being used as a verb.

sing because that is what they are doing in the sentence

explanation:

the simple predicate is the main verb in the predicate that tells what the subject does. example: my father fixed the dryer. read each sentence. draw a line under the complete predicate.