Borrow instead of buying if it exists.

[fenglish]

I want to confirm if I should use "verb+ing" or just "verb" form.

This is the use case:

I prefer you to borrow a book from library instead of buying a new book from store.

If we both known what we are talking is related to books, and I want to send you a message without mentioning the word "book":

A: Borrow instead of buying if it exists.
B: Borrowing instead of buying if it exists.

Which one is correct? Or both correct or both wrong?

 

[emsr2d2]

I want to confirm if I should use "verb+ing" or just "verb" form.

This is the use case: [I don't know what this sentence means - mod]

I would prefer that you to borrow a book from library instead of buying a new book from a store.

If we both known that what we are talking about is related to books, and I want to send you a message without mentioning the word "book", should I use A or B below?

A: Borrow instead of buying if it exists.
B: Borrowing instead of buying if it exists.

Which one is correct no question mark here or are both correct/wrong? or both wrong?

Please note my comments and corrections above. Neither A nor B is natural. What do you mean by "if it exists"? Do you mean "If that book is in the library, I'd prefer that you borrow it rather than buying it"?

With regards to your main sentence (starting "I would prefer"), you don't need to say "a new book" - say "it". Also, there's no need to say "from a store". It's redundant because you already used "buy".

 

[teechar]

... borrow a book from library instead of buying a new book from store.

Who is saying that sentence, and who are they saying it to? Note that "library" (the same as "store") is a singular countable noun, so it should be "a/the library".