The sentence that begins with if known as conditional sentence.
Remember, had, were, in case, unless, provided, provided that, providing that can be used instead of If.
Try to understand If Clause and Main Clause
|If Clause||Main Clause|
|1. If I wake up early,||I go jogging.|
|2. If I have enough money,||I will go to Japan.|
|3. If I have enough time,||I’ll watch the football match.|
|4. If I had wings,||I would fly.|
|5. If I had time,||I would drop you off at school.|
|6. If he had been careful,||he wouldn’t have had that terrible accident.|
|Main Clause||If Clause|
|1. I go jogging||If I wake up early.|
|2. I will go to Japan||If I have enough money.|
|3. I’ll watch the football match||If I have enough time.|
|4. I would fly||If I had wings.|
|5. I would drop you off at school||If I had time.|
|6. He wouldn’t have had that terrible accident||If he had been careful.|
There are four types of Conditional sentences
|Conditional||Usage||If clause||Main clause|
|1. Zero||General truths||Simple present||Simple present|
|2. First||possible and very likely||Simple present||Simple future
|3. Second||possible but very unlikely||Simple past||subject+would/could/might+verb1|
|4. Third||impossible to fulfill||Past perfect||subject+would/could/might+have+verb3|
Four types of Conditional sentences in details
|Zero conditional||If + Simple present + Simple present|
|First conditional||It is possible and very likely that the condition will be fulfilled.
If + Simple present , sub + shall/will/can/may + verb1 + ext.
If + Simple present, Imperative sentence
|Second conditional||It is possible but very unlikely, that the condition will be fulfilled.
If + Simple past , sub + would/could/might+ verb1 + ext.
Or, Were I a bird, I would fly at large.
Or, Had I enough money, I would start a business.
|Third conditional||It is impossible that the condition will be fulfilled.
If +past perfect, sub + would/could/might+have+verb3+ext.
Or, Had I seen her before, I would have disclosed the truth.
|If I invite you, you (come). If it rains, I (not go) to school. If I want, he (give) me. If they ask, he (disclose). If I (see) him, I will call him. If you run in the rain, you (catch) cold. If you work hard, you (prosper) in life. Memory will not go out if it (rain). If you finish the work in time, you (get) a prize. If they come, I (be) happy. If you write the letter, I (post) it. If it (rain), I will not go to play. If he reads attentively, he (pass). If it rains, I (go) to the park. If I study today, I (go) to the party tonight. If I have enough money, I(buy) some new shoes. She (be) late if the train is delayed. She (miss) the bus if she doesn’t leave soon. If I see her, I (tell) her.
If her uncle (arrives), I would meet him. If I (know) her phone number, I would call her. If I got a student visa, I (get) a great chance to study abroad. If I (am) a king, I would help the poor. If you (come) here, I would give you the news. If he studied regularly and seriously, he (do) well in the examination. If I were a king, I (help) the poor. If he requested me, I (go) there. If they tried, they (succeed). If I were a bird, I (fly). If he came, I (go). If I had enough money, I (set) up a hospital. If you tried, you (do) it. If I had extra books, I (lend) him. If I had the wings of a Dove, I (fly) to you.
If he had studied very seriously, he (make) a bright result. If she had not missed the interview, she (get) the job. If I had had your number, I (call) you but I had forgotten it. I (order) a taxi if you had told me. I would not have said that if I (have) there. Had I the wings of a bird, I (fly) like a bird. If I had been a rich man, I (help) the poor. Had I been a rich man, I (help) the poor. We would have come, if he (invite) us.