<p>This will not show up on the SAT, but I’ll give a really simple answer in the off chance that it can help you understand the topic better.</p>
<p>I take it you are familiar with the difference between “a” and “the.” “The concert” is distinct in meaning from “a concert” because in the former case, the concert in question is defined-- it is a specific concert. In the latter case, it could be any concert-- it isn’t* defined.*</p>
<p>This is the difference between definite and indefinite articles. When you make the two nouns, “a concert” and “the concert,” into pronouns, you lose their respective articles. Both become “it.” However, from context, you can often derive what type of article you would use in front of the noun form of a pronoun. This is the simplest way to tell the difference in the singular case. </p>
<p>For example:</p>
<p>It was a good concert. → The/A concert was a good concert.</p>
<p>Almost certainly, the correct choice is the. The pronoun is definite. </p>
<p>Additionally, in the singular case, it is very hard to find instances of indefinite pronouns. But the concept is well illustrated anyway, and once you understand the difference between definiteness and indefiniteness, it should make intuitive sense in the plural case.</p>
<p>However, if you need a ‘test’ for plural pronouns, let’s come up with one. Compare:</p>
<p>“You know what they say: love is blind.” with
“They told you not to do that.” </p>
<p>In the latter case, you can replace “they” with “the teachers” or “the parents” or whatever. In the former case, you can’t really assign an article to whatever “they” is implied. “You know what the people say: love is blind,” could make sense. However, it is clumsy compared to “what people say,” dropping the article. Hence, we expand the test to plural pronouns. If no article is less awkward than a definite article, then the pronoun is indefinite.</p>