Let's say, I have two friends and each of them has a book.
In other words the OP wants to emphasize that both his friends have got a book.
Which of the sentences is correct?
(1) 'Books of my friends are nice.' (2) 'Book of my friends is nice.'
The first sentence proposed by the OP is neither idiomatic nor grammatical.
A grammatical sentence would be: (1) The books of my friends are nice.
Without context the second phrase proposed by the OP sounds as if there are two or more friends who share one book. A grammatical and more plausible-meaning phrase would be:
(2) The book of my friend is nice.
However, native speakers do not usually use the above construction, instead they will say:
(1) My friends' books are... and (2) My friend's book is....
Although sentence (1) My friends' books are nice is grammatical and idiomatic, it doesn't tell us how many friends the speaker has nor how many books each friend has got. Friend A might have two books while Friend B might have hundreds. If the speaker feels it is important to specify the number of friends, I would suggest the following
- Both my friends have got a nice book
- Each of my [two] friends has got a nice book
- My two friends each have a nice book
We use both to refer to two things or people together:
Both those chairs are occupied, I’m afraid. (The two chairs are
Are both your parents going to Chile? (Are your mother and father
going to Chile?)
used to refer to every one of two or more people or things, regarded and identified separately
- Each of the answers is worth 20 points.
Each is used in front of a singular noun and is followed by a singular verb:
Each student has been given his or her own email address.
The use of his or her sometimes sounds slightly formal and it is becoming more common to use the plural pronoun their:
Each student has been given their own email address.
When each is used after a plural subject, it has a plural verb:
They each have their own email address.
- Each referring to a subject
When we use each to refer to the subject of the clause, it usually appears in the normal mid position for adverbs, between the subject and the main verb, after the modal
verb or first auxiliary verb, or after be as a main verb:
We each agreed to help by contributing some money towards the cost.
We would each say a poem or sing a song.
Have you each signed the contract?
Husband and wife are each entitled to invest up to the maximum