Thanks for your answers about the words "was" and ''were." I understand about singular and plurals,

Question

What about "I wish I "were" a doctor?" I is not plural here. So why use the word "were?"

Answer 1

As a subjunctive, you use the past tense

Answer 2

In this case, "were" is the verb "to be" in the subjunctive mood. The subjunctive mood is used for sentences that are desires or contrary to fact. For example:
I wish I were a doctor.
If John were smarter, he would be able to become a doctor.

The reason you don't see the subjunctive much is that most of the time it just looks like the past tense. This particular "were" case makes up the majority of the cases where you'll actually notice a difference between subjunctive and indicative. See the source for more info on the subjunctive mood.

It has actually become somewhat common to say "I wish I was..." You hear it in songs all the time. It's technically incorrect, but once something becomes commonplace, who's to say it's wrong?

Answer 3

'According to traditional rules, you use the subjunctive to describe an occurrence that you [believe] to be contrary to fact...The verb in the main clause of these sentences must then contain the verb would or (less frequently) should; for example,
"If I were ten years younger, I would consider entering the marathon."
"If America were still a British colony, we would all be drinking tea in the afternoon."

So, use of the word "were" instead of the word "was" usually takes place in something called the subjunctive; that is, you are saying something about something that is not true--for example, I am not a doctor. So, I would say, "I wish I were a doctor."
We use the word "were" to show that being a doctor is not what we are at the present time. =)

Answer 4

It is correct to use the term "were" in this instance because it is a hypothetical statement. Was versus were for the subject depends on if the subject is plural or singular. The subject of this statement is I and the verb is wish. The statement "I were a doctor" is not the object doing something. One would switch to use of hypothetical verb tense.

Answer 5

Good reference for questions like this: The Elements of Style by Strunk & White. A slim volume that answers the stickiest of grammar questions.