correct any errors. Please check my answers.

Question: 12) Every player on the team, must give their best effort in the championship game.
Every player on the team, must give his or her best effort in the championship game.

Question: 13) Each person in the seminar must submit a sample of their work in the portfolio.
Each person in the seminar must submit a sample of his or her work in the portfolio.

Question: 14) Every girl at the tryout thinks they are not going to make the team.
Every girl at the tryouts thinks she is not going to make the team.

Question: 15) I’ve heard it said that you can get an abortion in almost any big city these days.
I've heard that one can get an abortion in almost any big city these days.

Question: 16) I took my dogs’ from their cages and gave them a thorough cleaning.
I took my dog from his cage and gave him a thorough cleaning.

Question: 17) I hope everybody will give this their best efforts.
I hope everyone will give his or her best effort.

Question: 18) College athletics are becoming more popular each year.
College athletics are becoming popular each year.

Question: 19) The dog or the cat are hiding under the porch.
The dog or the cat is hiding under the porch.

Question: 20) Transportation in this country, cars, boats, and trains, are becoming too expensive.
Transportation in this country, cars boats and trains is to expensive.

12. OK if you delete that comma.

13, 14, 15, 17, 19 = OK

16. How could you write this correctly and keep it in the plural?

18. The original reads better than the revision.

20. How will you correct this? http://grammar.ccc.commnet.edu/grammar/marks/dash.htm

how student can attain optional as given a chance as creatively, critically, productivity and meaningfully

Question 12: The correct answer is "Every player on the team must give his or her best effort in the championship game."

Explanation: In this sentence, the subject is "Every player on the team," which is singular. Therefore, we should use the singular pronoun "his or her" instead of the plural pronoun "their."

Question 13: The correct answer is "Each person in the seminar must submit a sample of his or her work in the portfolio."

Explanation: Similar to the previous question, the subject "Each person in the seminar" is singular. Hence, we should use the singular pronoun "his or her" instead of the plural pronoun "their."

Question 14: The correct answer is "Every girl at the tryouts thinks she is not going to make the team."

Explanation: In this sentence, we are referring to each girl individually, so we should use the singular pronoun "she" instead of the plural pronoun "they."

Question 15: The correct answer is "I've heard that one can get an abortion in almost any big city these days."

Explanation: "It" is a vague pronoun in this sentence, and we should avoid using such pronouns. Instead, we can rephrase the sentence to clarify who can get an abortion by using the pronoun "one."

Question 16: The correct answer is "I took my dog from his cage and gave him a thorough cleaning."

Explanation: In this sentence, the possessive adjective "my" shows that we are talking about one dog. Therefore, we should use the singular pronoun "him" instead of the plural pronoun "them."

Question 17: The correct answer is "I hope everyone will give his or her best effort."

Explanation: Similar to the previous questions, the pronoun "everyone" is singular. Hence, we should use the singular pronoun "his or her" instead of the plural pronoun "their."

Question 18: The correct answer is "College athletics are becoming popular each year."

Explanation: This sentence is grammatically correct, and no errors have been made.

Question 19: The correct answer is "The dog or the cat is hiding under the porch."

Explanation: The subject "The dog or the cat" is considered singular, and we should use the singular verb "is" instead of the plural verb "are."

Question 20: The correct answer is "Transportation in this country, cars, boats, and trains, is too expensive."

Explanation: In this sentence, the subject "Transportation in this country, cars, boats, and trains" is considered singular, and we should use the singular verb "is" instead of the plural verb "are." Also, the word "to" is missing before "expensive."