Answer:
All of the shirts(S) have(V) a green collar
The singer(S), along with a few others, plays(V) the guitar on stage.
Sandals(S) and towels(S) are(V) essential items for the beach.
Explanation:
Subjects are the main object of a sentence. Verbs are the actions of the subject, shirts: have, singer: plays, sandal and towels: are.