When none, neither, either and any are followed by of + plural noun or pronoun, they are normally used with singular verbs in a formal style in British English. Plural verbs are more common in informal British English and American English.
- None of these answers is correct. (Formal British)
- None of these answers are correct. (Informal British; American)
- Neither of my parents has been outside India. (Formal)
- Neither of my parents have been outside India. (Informal)
Another, a/an + adjective
We often use plural expressions of quantity after another and a/an + adjective.
- I will be staying for another two weeks.
- I have been waiting for a good four hours.
- I spent a happy thirty minutes playing with the kids.
Every is usually used with singular nouns, but can be used before plural expressions in measurements of frequency.
- Buses leave every five minutes.
- I visit them every six weeks.
Sort of, kind of, type of etc
We do not usually use the article a/an after sort of, kind of, type of etc. But note that articles are often used in an informal style.
- What sort of bird is that? (Formal)
- What sort of a bird is that? (Informal)
Sort of, kind of and type of are usually followed by a singular noun.
- This sort of car is very expensive.
Sort of, kind of and type of can also be followed by plural nouns in an informal style.
- I am interested in any sort of cars.