4

Which sentences are correct?

  • 1- The cover of book is green.
  • 2- The cover of the book is green.
  • 3- A cover of book is green.
  • 4- A cover of a book is green.

When should we use a or the?

3

1- The cover of book is green.

Error: the word "book" is a singular count noun, it needs an article.

2- The cover of the book is green.

OK: a book known to the reader is described, hence the.

3- A cover of book is green.

Error: the word "book" is a singular count noun, it needs an article.

4- A cover of a book is green.

OK: one of the covers of a book unknown to the reader is described.

The rule of the thumb is: if you see a noun like "book" which is countable (you can have 1, 2, 3 or more books) and it is in the singular form in your sentence (you can put the word one before it: one book), you should use an article. Or some other determiner, like my.

Both the word cover and the word book are singular countable nouns, so they both take an article (or other determiner). The meaning will change depending on which article or other determiner you choose.

As BobRodes points out, one other option, which you failed to mention, is

The cover of a book is green.

The meaning is: there's some unspecified book, and its cover is green.

As J.R. points out, one additional grammatical option is

A cover of the book is green.

The meaning is: the book has been mentioned before, and has two or more covers, one of which is green.

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  • 1
    You could also say "The cover of a book is green", which would mean that an unspecified book's cover is green. "A cover of a book is green" implies that the book could have any number of covers, one of which is green. – BobRodes Dec 12 '14 at 4:58
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    nicely explained. +1 However, worth to mention that in the style of headlinese, articles are often dropped out. For a learner, it's very important to know! :) – Maulik V Dec 12 '14 at 6:04
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    There's also "A cover of the book is green," implying the book has at least two covers, at least one of which is green. Also, while 4 is "OK" grammatically, as you say, I think 2 seems much more likely to be used in everyday speech. "A cover of a book is green" is so vague that the sentence hardly seems useful; it's akin to saying: "Somewhere there exists some book that has a green cover" (reminds me of: "I'm thinking of a number between one and a million"). – J.R. Dec 12 '14 at 8:11
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    On the other hand, "The cover of a book is green" can also be used to say that by definition, if something is a book, it has exactly one cover, and that cover is green. "A cover of a book is green" is sometimes used to avoid that interpretation: there are lots of things that can be called "cover of a book", and you're only commenting on one of those things, without specifying which. – hvd Dec 12 '14 at 10:31
1

For this purpose, only 2 and 4 are technically correct.

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