Pronoun agreement errors are an especially confusing type of ACT English question because people often misuse pronouns, especially when you speak. In fact, I just made a pronoun mistake: can you spot it?
Take a closer look at the second half of my first sentence: "people often misuse pronouns, especially when you speak." Who is "you" referring to here: "people." However, the correct pronoun for the third person plural is "they." The correct version of the sentence is "people often misuse pronouns, especially when they speak."
On the ACT English section, you'll be expected to spot these kind of errors in a variety of different contexts. I'll go over both the basic rules for pronouns and the common mistakes you'll see on the test, so that you can approach the test with confidence.