Is it grammatical?

Are you sure, Roberta? What if the dad is dead? Then the sentence would work.

"won't ever" is wrong. It should be "wouldn't ever."

Roberta wrote:

"won't ever" is wrong. It should be "wouldn't ever."

I don't believe that "won't ever" is wrong. Prove it!

I can't see it being "wouldn't". Assuming you're talking about card games, once the hands are folded and returned to the deck, if you didn't see the card, you're never going to know what it was, "it's an ongoing state of non-knowledge. "wouldn't' is a past tense form. "won't" is an ongoing tense form, so would seem to be more appropriate, cause your dad didn't know in the past, doesn't know now, and won't know in the future either.

stuh505 wrote:

Roberta wrote:

"won't ever" is wrong. It should be "wouldn't ever."

I don't believe that "won't ever" is wrong. Prove it!

The first phrase has an "if", so it's conditional. So you need to use "would" if that condition is met. So "wouldn't" is correct here.

No, we're not saying you can't use "if" only with conditionals, but you do use them with conditionals... and upon further reflection, isn't "would" a future conditional of "will"?

Well that's true. So we need to know more about the first sentence. Could you, J-B, quote the sentence before and the sentence following that one, to make the context clearer.

(1) In one scene in a short story I recently read, the main character goes back in time and happens to bring a few gold pieces back to the present with him. (2) The gold pieces turn out to be incredibly valuable. (3) This short story reminded me of the baseball card collecting craze, it being an interesting facet of American pop culture. (4) Buying and saving baseball cards means spending very little money on something that might turn out to be worth big bucks in the future.
(5) My dad collected baseball cards when he was a kid, and no one back then thought they'd be worth anything. (6) Someone like my dad used up his allowance every week just because he wanted to collect all of his favorite players?-Roy Campanella, in my dad's case. (7) By dedicating the bulk of his weekly income to adding player after player to his collection, my father declared his dedication to the players.
(8) Baseball is a highly profitable sport, and so baseball card collecting has become one. (9) Everyone has heard of one baseball card in its original wrapping commanding an absurdly high price, and now everyone is positive that his or her shoebox filled with old baseball cards contains at least one card worth millions. (10) But if my dad had that one card, he won't know it. (11) Way before he realized it, his mother had gotten rid of them.

5. Of the following, which best revises the underlined part of sentence 10, which is reproduced below?
But if my dad had that one card, he won't know it.
(A) card, they would never realize it.
(B) card; he would never realize it.
(C) card, how could he realize it?
(D) card, my dad won't ever realize it.
(E) card?-he never realized it.

5. The correct answer is D.
The main problem is tense. The first half of the sentence sets up a conditional sequence, but the verb is simple past tense: if my dad had and won't know it don't fit together correctly. Of the answers, only A and D solve this tense problem. But A introduces a new problem by creating a mismatched pronoun. The plural they cannot act as a pronoun for the singular my dad. That means choice D must be the right answer.

5. The correct answer is D.
The main problem is tense. The first half of the sentence sets up a conditional sequence, but the verb is simple past tense: if my dad had and won't know it don't fit together correctly

I never knew learning English was this complicated.

But, hooray:

J-B's crazy textbook wrote:

5. The correct answer is D.
The main problem is tense. The first half of the sentence sets up a conditional sequence, but the verb is simple past tense: if my dad had and won't know it don't fit together correctly

which is what I said, more or less.