If+Conditional Clauses
1st Types 1.There is a condition possible to fulfill e.g. typeif clausemain clause ISimple Present will-future (or Modal + infinitive) typeif clausemain clause IIf I study,I will pass the exam.
2nd Type 2 In theory possible to fulfill. e.g. typeif clausemain clause IISimple Past would + infinitive * typeif clausemain clause II If I studied,I would pass the exam.
3 rd Type typeif clausemain clause IIIPast Perfectwould + have + past participle * 3. Condition not possible to fulfil typeif clausemain clause IIIIf I had studied,I would have passed the exam.