Pronoun Answer 21

21. Shouting "Eureka!" over and over, he ran through the streets of Syracuse. They must have been amazed to see him.

Rewrite:

21. Shouting "Eureka!" over and over, he ran through the streets of Syracuse. The townsfolk of Syracuse must have been amazed to see him.

Why?

"They" did not refer to any plural noun in particular. The "townsfolk of Syracuse" are implied as the antecedent; however, they are not explicitly named.