When do I use is or does when I ask a question? For example,
- Is your item still for sale?
- Does your item still for sale?
I am not sure which one to use.
When the verb in a statement is neither a primary auxiliary verb (be, have, do) nor a modal auxiliary verb (will, would, can, could, may, might, shall, should, must, ought to, used to), do is used to form a question from it. Thus, ‘You know where my house is’ becomes ‘Do you know where my house is?’
Meanwhile, when the verb in a statement is a primary auxiliary verb or a modal auxiliary verb, then a question is formed from it by placing the verb before the subject. That means that ‘Your item is still for sale’ becomes ‘Is your item still for sale?’
Barrie Englands answer is great. However, I have a feeling those seeking an answer will be at a level where they will also confused by the neither/nor structure.
For Primary auxiliaries (be/have/do), and Modal auxiliaries (will, would, can, could, may, might, shall, should, must, ought to, used to):
Simply reverse the statement to form the question.
For all others use ‘do’ to form questions:
Place the verb before the subject.