Please add the correct punctuation mark (apostrophe) to the following question: My stepbrothers car needs new upholstery and new tires.
In punctuation marks, the apostrophe seems to cause the most trouble for students. The concept in question here is the difference among possession, plurals and the s in third person singular verbs. The correct placement of the apostrophe is between the r and the s as in stepbrother's car. The apostrophe here shows that the car belongs to the stepbrother. The s in needs is there to show that the verb agrees with the third person singular subject; a simpler example of this is "he runs." The s at the end of tires is to show a plural noun meaning that the car would need more than one tire. Plurals do not need apostrophes; therefore, the only apostrophe required in this sentence is the one indicating possession--that the car belongs to the stepbrother. The link below will help you learn how to use apostrophes, and since they are often used incorrectly, this tool could help you a great deal.