If you study harder, you will surely pass the coming exams with good results. (Use the simple present for first conditional.)

If the weather weren't too bad, we would go swimming. (Correct usage of second conditional for unreal situations.)

If I had known he wasn't at home, I wouldn't have gone all the way to his house. (Use past perfect for third conditional.)

I asked him how far it was to the station if I went there by taxi. (This sentence is correct.)

Unless you have a passport, you cannot register for a course abroad. (Correct form of "can" in negative conditions.)

I wish these students hadn't talked too much in class. (Past perfect for regrets about the past.)

I would bring my umbrella in case it rains on my way home. (Use the simple present for "in case".)

She wishes she were the most beautiful girl in the world. (Use "were" for wishes about the present.)

If today were Sunday, staying in bed and watching a thriller would make me happier than anything else. (Use "were" for unreal conditions.)

I wish my father would give up smoking in the near future. (Use "would" for future wishes.)

If Lucia were here now, she would find out the truth about her uncle's accident. (Use "were" for unreal present conditions.)

Unless we leave a bowl of water under the sun, it will evaporate. (Correct usage of "unless" in conditional sentences.)

If I had known the time when the match started, I would have told you. (Use past perfect for third conditional.)

If I were you, I would go to the dentist's and have the tooth checked. (Use "would" for second conditional.)

If you hadn't left the car unlocked, it wouldn't have been stolen. (This sentence is correct.)

What would happen if I pressed that red button? (Use "if" to form a question about a hypothetical situation.)

If the weather were fine today, we would go to the beach. (Use "were" for unreal conditions.)