GMAT Sentence correction

[Mark53]

Hi everyone,

I'm training for GMAT. Here are some questions where my answer was not the right one but I didn't get any further explanations. The correct answer is in the sentence. I'd be glad if you could explain me why my choice was wrong.

If I |would have known| about the team tryouts, I would have signed up for them.
My answer : had been told

Valarie claims that cats |make the best pets|.
My answer : are the best pets

The helium- filled balloon |rose into the air|.
My answer : rose in the air

During Colonial days, a |schoolroom| looked rather empty.
My answer : school room

Quebec |rises magnificently above| above the St. Lawrence River.
My answer : rises in a magnificent way

Jessica Mitford wrote The American Way of Death, a best-selling book, |which led eventually| to an official investigation of the funeral industry.
My answer : that eventually led

If the books |were cataloged| last week, why haven’t they been placed on the shelf?
My answer : have been cataloged

My biggest interrogation lies in the first sentence. I didn't know that "would" could follow a "if".

Thanks in advance,
Mark

[Tdol]

Was this a computer test? If so, the first could be an error.

[Mark53]

Well, I found the test on the Web. So, you agree on the fact that the answer they give for the first sentence does not seem correct, right?

Mark

[Tdol]

Yes
2 We often talk about animals making good pets and individual animals being good pets.
3 Rose into- it went from the ground, so it didn't start in the air. If it rose in the air, it would not have started from the ground
6- Don't use 'that' as a relative pronoun in a non-restrictive clause (after a comma)
7 When we are questioning the truth of a past event, we the past tense. The past perfect would be imagining the oppositie of an established fact

[Mark53]

Hi Tdol,

Thanks for your reply. Though, I don't understand the problem in sentence 6. Could you please give me a case where "that" must be used? For me, the were rather equivalent.

Thanks,
Mark