I am wandering if my answers and rationale are correct. The capital X denotes my chosen answer and my rationale follows the statement choices.

Comprehensive Grammar CheckPoint
Read the following sentences, and focus on the grammar area specified in the left column. Then,
complete Appendix H by selecting the correct sentence (a or b) for each number and providing an
explanation of why you made that choice.

Subject-verb agreement
1a. Did you know a famous animal-rights activist has criticized horseracing
because of the dangers involved?
1b. Did you know a famous animal-rights activist have criticized horseracing
because of the dangers involved?
“Activist” is a singular subject; therefore the verb must also be singular.

Subject-verb agreement
2a. Peer editing academic papers require critical-thinking skills and diplomacy.
2b. Peer editing academic papers requires critical-thinking skills and diplomacy.
The emphasis is on the action “peer editing” and not the subject of the action “academic papers”. Therefore, the correct form is requires.

Subject-verb agreement
3a. Vitamins that are sold in a health-food store are not regulated by the Food
and Drug Administration.
3b. Vitamins that are sold in a health-food store is not regulated by the Food
and Drug Administration.
“Vitamins” is a plural subject; therefore the verb must also be plural.

Using regular and irregular verbs
4a. John has become a rather good actor.
4b. John has became a rather good actor.
Sentence A uses the correct participle form “become” in conjunction with “has”.

Using regular and irregular verbs
5a. Some athletes have taken drug tests to prove they are not on steroids.
5b. Some athletes have took drug tests to prove they are not on steroids.
The use of the helping verb “have” along with the past tense action “taken” makes sentence A correct.

Using regular and irregular verbs
6a. I lay my book on the table, but now I cannot find it.
6b. I laid my book on the table, but now I cannot find it.
The use of “lay” in sentence A is referring to something “I” do, whereas sentence B refers to something “I” did. Sentence B uses the correct action in respect to the tense of the rest of the sentence.

Using the correct form of be and have in the present tense
7a. I was interested in working on the presidential campaign if the opportunity
still exists.
7b. I am interested in working on the presidential campaign if the opportunity
still exists.
The sentence speaks in the present tense; therefore “am” is the correct verb.

Verb form and verb tense
8a. Since American Idol premiered on television, many talented contestants
have appeared on the show.
8b. Since American Idol premiered on television, many talented contestants
appeared on the show.
The helping verb “have” is used in conjunction with the linking verb “appeared”. This statement is speaking in the present perfect tense.

Verb form and verb tense
9a. The ancient Egyptians built pyramids as burial sites for their leaders.
9b. The ancient Egyptians have built pyramids as burial sites for their leaders.
This statement is written in the past tense with the indicative mood, therefore no helping verb is warranted.

Identifying antecedents
10a. The antecedent in the following sentence is students: Students in online
classes have to be organized to keep up with their assignments.
10b. The antecedent in the following sentence is class: Students in online
classes have to be organized to keep up with their assignments.
The pronoun “their” is clearly defined as “Students” therefore the correct antecedent is “Students”.

Identifying antecedents
11a. The antecedent in the following sentence is Doctors: Doctors should
schedule more time for patients so they do not spend so much time in the
waiting room.
11b. The antecedent in the following sentence is patients: Doctors should
schedule more time for patients so they do not spend so much time in the
waiting room.
The pronoun “They” is clearly defined as “patients” therefore the correct antecedent is “patients”.

Pronoun-antecedent agreement
12a. When a driver wants to buy a new vehicle, he or she usually test drives
them.
12b. When a driver wants to buy a new vehicle, he or she usually test drives it.
“Them” is a vague pronoun. “it” is clearly defined as the new car.

Pronoun-antecedent agreement
13a. Most presenters spoke without looking at his or her notes.
13b. Most presenters spoke without looking at their notes.
This statement is speaking about the collective noun “presenters”, therefore “their” is clearly defined.

Pronoun-antecedent agreement
14a. You may rent a movie or a video game for just one night if they are new.
14b. You may rent a movie or a video game for just one night if it is new.
“They” represents a collective pronoun. There is no collective pronoun in either sentence. A pronoun must match and agree with the noun it references

Pronoun-antecedent agreement with indefinite pronouns
15a. Neither the mayor nor the council members have filed their reports.
15b. Neither the mayor nor the council members have filed his reports.
“Neither” sometimes takes a plural verb when followed by a prepositional phrase beginning with “of”. When “or” is used, the subject closer to the verb determines whether the verb is singular or plural.

Pronoun-antecedent agreement with indefinite pronouns
16a. Anyone who requests a copy of the game may have it for their video
library.
16b. Anyone who requests a copy of the game may have it for his or her video
library.
“Anyone” is a singular indefinite pronoun. A pronoun must always match and agree with the noun it references or replaces.

Pronoun-antecedent agreement with indefinite pronouns
17a. Each of the applicants must submit his or her completed form to the
interviewer.
17b. Each of the applicants must submit their completed forms to the
interviewer.
The word “each” is a singular antecedent so the pronoun “his or her” is correct.

I'm not seeing any X's ...

Subject-verb agreement

1a. Did you know a famous animal-rights activist has criticized horseracing
because of the dangers involved?
1b. Did you know a famous animal-rights activist have criticized horseracing
because of the dangers involved?
“Activist” is a singular subject; therefore the verb must also be singular.
So you’re choosing which one? 1a or 1b?

Subject-verb agreement
2a. Peer editing academic papers require critical-thinking skills and diplomacy.
2b. Peer editing academic papers requires critical-thinking skills and diplomacy.
The emphasis is on the action “peer editing” and not the subject of the action “academic papers”. Therefore, the correct form is requires.
Your conclusion is correct – “requires” is the correct verb choice – but your terminology is off. “Peer editing” is the subject, and it’s singular; therefore, you need “requires” which is the singular form of the verb.

If you want further help with this, be sure to let us know which of each pair you have chosen as correct – and please be clear!

Thanks.

My apologies, I see now that I forgot to include my answer choices.

1A, 2B, 3A, 4A, 5A, 6B, 7B, 8A, 9A, 10A, 11B, 12B, 13B. 14B, 15A, 16B, 17A.

Your answers and rationales are mostly correct. However, there are a few corrections to be made:

For question 1, the correct answer is actually 1a. The rationale you provided is correct, but you chose the incorrect sentence.

For question 12, the correct answer is 12a. The rationale you provided is incorrect. In this case, "them" is not a vague pronoun, but rather a gender-neutral pronoun used to refer to a singular antecedent.

For question 14, the correct answer is 14b. The rationale you provided is incorrect. Even though there is no collective pronoun in either sentence, the verb "rent" in the sentence is referring to one movie or one video game, so the pronoun "it" should be used.

Overall, you did a good job in analyzing the subject-verb agreement and pronoun-antecedent agreement in these sentences. Keep up the good work!