Which of these is a complete sentence?

Although the weather is sometimes warm in early March.
The old saying, “In like a lion, out like a lamb.”
Forecasters predicted six more weeks of winter this year.

Forecasters predicted six more weeks of winter this year.

Identify the choice that best describes the underlined word in the sentence.

With practice, both Kendra and "Jason" mastered the violin.
part of a compound subject
part of a compound predicate
a direct object

The underlined word "Jason" is part of a compound subject.

Identify the choice that best describes the underlined word in the sentence.

My friend Jorge can play the guitar and sing.
a verb phrase
an incomplete sentence
a compound predicate

The underlined word "sing" is part of a verb phrase.

Identify the choice that best describes the underlined word in the sentence.

My friend Jorge can "play" the guitar and sing.
a verb phrase
an incomplete sentence
a compound predicate

The underlined word "play" is a verb.