Pronouns must agree with their antecedents in number and person. Do not use a plural pronoun for a singular antecedent or a singular pronoun for a plural antecedent. Do not shift person within a sentence. In particular, do not use the second-person pronouns you or your to refer to a first-person or third-person antecedent.

In this sentence, “boys” was shifted incorrectly to “he”. “he” should be “they” (with “jacket” becoming “jackets”).

 Pronouns must agree with their antecedents in number and person. In this example, “a man” (singular) is shifted incorrectly to “they” (plural). “they” should be “he”.

Pronouns must agree with their antecedents in number and person. Do not use a plural pronoun for a singular antecedent or a singular pronoun for a plural antecedent. Do not shift person within a sentence. In particular, do not use the second-person pronouns you or your to refer to a first-person or third-person antecedent.

In this example, “scientists” (plural, third-person) shifts to “you” (singular, second-person). “you” should be “they”.

Pronouns must agree with their antecedents in number and person. Do not use a plural pronoun for a singular antecedent or a singular pronoun for a plural antecedent. Do not shift person within a sentence. In particular, do not use the second-person pronouns you or your to refer to a first-person or third-person antecedent.

In this example, there are three pronouns to deal with. “her” clearly refers to Karen, while “him” clearly refers to the son. It is unclear who “their” is referring to. “their” is plural, but must be referring to Karen (singular) or her son (singular). “their” should be “his” or “her”.

Pronouns must agree with their antecedents in number and person. Do not use a plural pronoun for a singular antecedent or a singular pronoun for a plural antecedent. Do not shift person within a sentence. In particular, do not use the second-person pronouns you or your to refer to a first-person or third-person antecedent.

In this example, there are two pronouns to seal with: “he” and “their”. “he” clearly refers to Joshua, but it is unclear who “their” (plural) refers to. Josh and Marty are both singular, so “their” should be “his”.

Pronouns must agree with their antecedents in number and person. Do not use a plural pronoun for a singular antecedent or a singular pronoun for a plural antecedent.

In this example, “he” is singular” while referring to “students” (plural). “he” should be “they”.

Pronouns must agree with their antecedents in number and person. In this example, there are two pronouns to consider: “his” and “it”. “his” (singular) clearly refers to Chris (also singular), while “it” (singular) seems to refer to “classes” (plural). “it” should be “they”.

Pronouns must agree with their antecedents in number and person.  Do not shift person within a sentence. In particular, do not use the second-person pronouns you or your to refer to a first-person or third-person antecedent.

In this example, there are two pronouns to consider: “her” and “you”. “her” refers to Rachel, but “you” represents a shift in person. Rachel and her mom are both third person, so “you” (second-person) should be “she” (third-person).

Pronouns must agree with their antecedents in number and person.  Do not shift person within a sentence. In particular, do not use the second-person pronouns you or your to refer to a first-person or third-person antecedent. In this example, there are to pronouns to consider: “his” and “you”. “his” clearly refers to David, while “you” (singular, second-person) represents a shift in number and in person. “you” should be “they” (plural, third-person).

Pronouns must agree with their antecedents in number and person. Do not use a plural pronoun for a singular antecedent or a singular pronoun for a plural antecedent. Do not shift person within a sentence. In particular, do not use the second-person pronouns you or your to refer to a first-person or third-person antecedent.

There are four pronouns in this sentence. Three of them are written in the third-person (“her”, “they”, and “them”), while “you” represents a shift to second-person. The end of this sentence can be revised from “you cannot beat them.” to something like “they cannot be beat.”