Conditional Sentences / If-Clauses Type I, II and III

Conditional Sentence Type 1

→ It is possible and also very likely that the condition will be fulfilled.

Form: if + Simple Present, will-Future

Example: If I find her address, I’ll send her an invitation.

→ It is possible but very unlikely, that the condition will be fulfilled.

Form: if + Simple Past, Conditional I (= would + Infinitive)

Example: If I found her address, I would send her an invitation.

→ It is impossible that the condition will be fulfilled because it refers to the past.

Form: if + Past Perfect, Conditional II (= would + have + Past Participle)

Example: If I had found her address, I would have sent her an invitation.

Sometimes Conditional Sentences Type I, II and III can also be used with other tenses.