What is wrong with these sentences then? I have been reading and studying abouy subject-verb agreements and I keep getting this wrong so I need help becauase I just got these wrong.

1. A number of my friends have bought new cars recently.
2.Each of his sisters go to a different school.
3. Robert's friend Steve, as well as his wife, are going to the fair.
I pocked number 3 and it was wrong so what are wrong in theses sentences. I'am totaly lost.

The first sentence is correct. In this sentence, the subject is "number" and used as a plural. Therefore, "have" is the correct verb. By the way, I checked the usage and definition of "number" at Dictionary.com to be sure of this usage.

The subject of the second sentence is "each" which is clearly singular. Since "of his sisters" is a prepositional phrase, it cannot contain the subject. Would you say "she go" or "she goes"?

"Steve" is the subject of the third sentence and is singular. Would you say "he is" or "he are"?

This site may make subject-verb agreement clearer to you.

http://owl.english.purdue.edu/owl/resource/599/01/

Let's break down each sentence and identify the issues with subject-verb agreement:

1. A number of my friends have bought new cars recently.
- The subject of the sentence is "a number of my friends," which is a collective noun phrase. In this case, "a number" acts as a non-specific quantity. Even though "number" may imply a singular noun, in this context, it is treated as plural. Therefore, the correct verb form should be "have" instead of "has."

2. Each of his sisters go to a different school.
- The subject of the sentence is "each of his sisters." The word "each" is singular, which means the verb should also be singular. Instead of "go," it should be changed to "goes."

3. Robert's friend Steve, as well as his wife, are going to the fair.
- The subject of the sentence is "Robert's friend Steve, as well as his wife." In this case, there are two subjects connected by "as well as," which is a phrase that introduces additional information. When using this construction, the verb should agree with the first subject, "Robert's friend Steve," which is singular. Therefore, the correct verb form should be "is" instead of "are."

To avoid confusion, here's a revised version of each sentence with the correct subject-verb agreement:

1. A number of my friends have bought new cars recently.
2. Each of his sisters goes to a different school.
3. Robert's friend Steve, as well as his wife, is going to the fair.

Remember, subject-verb agreement is a grammatical concept that requires careful attention to the relationship between the subject (who or what the sentence is about) and the verb (the action or state of being). I hope this explanation helps you understand and apply subject-verb agreement correctly in the future!