for teachers of English and their students
What article is used before nouns followed by a number or a letter?
Do not use any article before a noun identified by a number or a letter. The noun is already considered determined by the identifier.
For example, a phrase like this:
Please refer to columns A and B.
(you will be asked to create an account if you do not have one)
At PhraseCat.com you can study grammar points and practise their application right away.