Which of these sentences is correct?

If you knew you were going to die tomorrow, what would you do today?

This is the correct statement, but you need to use a comma, not a hyphen, to separate the clauses.

This is called an "unreal conditional" phrase. When we use "If" to introduce a condition that we expect not to be true (i.e., we don't expect we will really die tomorrow), we use "were" as the verb, regardless of the subject. ("If I were you, I wouldn't do that") The "were" alerts the listener that the condition is "unreal" or "not expected"

The first one sounds best, but you just need a comma. Like this: If you knew you were going to die tomorrow, what would you do today?

number 1 is definitely best,

cant think of a way i could word it much better. use a comma instead of a - tho

You'd is short for 'You Would' so 'if you knew you would die tomorrow - what would you do today?'

its not bad but the other ones better

The first is the best, but how about swapping it around, like 'what would you do today if you knew you'd die tomorrow?'

Just an idea hahaha :D

They are both correct English, but they have slightly different meanings.

The first is the more usual. The second suggests that dying tomorrow would be a conseqence of what you do today. It would be more correct to use a comma rather than a dash.

I think it's sounds better to say, What would you do today if, you knew you were going to die tomorrow?

first is almost perfect, as mentioned you should have used a comma,

you could also write it like this

" What would you do today if you knew that tomorrow you were going to die? "

If you knew that tomorrow you were going to die, what is it that you would make sure of doing today.

Note the comma, not a dash.

Otherwise your versions are fine.

number 1 is BETTER after changing the dash into a comma, note the capitalization of better. some replies use the word best but since there are only two options it should be better. you would use best if there wre more than two options. remember the progression, good for one, better for two and best for more than two i.e. good better, best.

Personally, I would say it as indicated in example 1, purely because it sounds more correct. Although, example two is not wrong either.