I will tell you the truth if you will promise not to get angry.
...if you promise...
What will you say if he asked you to marry him?
What will you say if he asks... / What would you say if h asked...
If I would you, I would come back.
If I were you...
If Tania move to London, she will spend a lot of money on rent.
If Tania moves...
If you won a lottery, what you would buy first?
...what would you buy...
I would to buy the tickets now if I were you.
I would buy...
If I don’t have arachnophobia, I would buy a pet tarantula.
If I didn't have...
If I known the truth, I would tell you!
If I knew...
How would you react if you see a mermaid?
...if you saw a mermaid?
If I were can travel for free, I would go around the world.
If I could travel...
If you would be American, you would have a very different life.
If you were an American...
I might be late if my sister don’t pick me up.
...if my sister doesn't pick me up.
