Either/Or and Neither/Nor

Either/Or and Neither/Nor

The pairings either/or and neither/nor are normally used to group two people or things.

They are sometimes used to group more than two things, however this is grammatical error and should be avoided where possible.

Negative & Positive usage:

Either / or	is used in the affirmative sense when referring to a choice between two possibilities
	We can either go out now or later after dinner.
Neither / nor	is used in the negative sense when expressing that two or more things are not true
	Neither my mother, nor my father like dogs.

Group usage:

Two elements	He could neither laugh nor cry at the sight before him.
	‘It is either you or me, we cannot both go.’
	(Either) John or Mum has the keys to the house. - the verb is used in the singular – reference to verb usage
	Mum could not find the keys in her handbag or on the hook. - the word either can also be omitted when using ‘or’
Three elements	Neither the parents, nor the teachers and the headmaster noticed that the school was on fire. You cannot say: Neither the parents nor the teachers, nor the headmaster, noticed that the school was on fire.

Avoid Double Negatives:

neither/nor	this pair denotes a negative statement, however, be careful not to use them to create a double negative statement
incorrect	John did not find the book neither on his desk nor in his bag. X
correct	John found the book neither on his desk, nor in his bag. John did not find the book, either on his desk or in his bag.

When a double negative is correct:

not + un

She is not unattractive. (this does not mean that she is not attractive, but that actually she is)

Either/Or and Neither/Nor

With verbs: Singular or plural?

Both elements in the singular	Verb will be in the singular.
	Either your mother or your father has to attend the school meeting (mother and father are singular nouns, so the verb has, is singular)
	Neither John nor Lucy is going to the party. John and Lucy are singular, so the verb is, is singular
Correct usage	Neither Jean nor her brother is at school today. Either my dog or my cat has eaten my homework.
Incorrect usage	Neither my brother nor my sister do as they are told. the verb should be does as my brother and my sister are singular nouns.
One of the elements in the plural	Verb has to be in the plural
	Either John or the boys are going to take the dog for a walk. the boys is a plural noun, hence a plural verb is required: are
	Neither the headmaster, nor the teachers were prepared for the flood in the school hall. the teachers is a plural noun, hence a plural verb is required: were
NB Proximity Rule	There was neither milk nor vegetables at the supermarket. under the proximity rule, the noun closest to the verb governs whether it is singular or plural
	however, please note that this rule is under debate and therefore if there is a plural noun, it is safer to use the plural verb.