1. CONDITIONALS: REVISION
Conditional Sentence Type 1
Form: if + Simple Present, will- future
If I find her address, I’ll send her an invitation.

2. Conditional Sentence Type 2
It is possible but very unlikely, that the condition will be fulfilled.
Form: if + Simple Past, Conditional I (= would + Infinitive)
If I found her address, I would send her an invitation

3. Conditional Sentence Type 3
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)
If I had found her address, I would have sent her an invitation.

4. Quick Revision
A father asks his son why he hasn’t done homework. What do you think he is going to answer?

5. If I do my homework, I’ll get good grades
If I do my homework, I’ll get good grades. If I get good grades, you’ll send me to university. If I go to university, I’ll graduate and get a job. If I get a job, I might get fired. If I get fired, I could go bankrupt and lose everything. That’s why I didn’t do my homework!”—

7. Mixed conditionals
Unreal conditionals (type II + III) sometimes can be mixed, that is, the time reference of the if clause may be different from the one of the main clause.

8. If I had taken an aspirin, I wouldn’t have a headache now
Past –> Present
If I had taken an aspirin,
I wouldn’t have a headache now

9. Past –> Future
If I had known that you are going to come by tomorrow,
I would be in then

10. If she had enough money, she could have done this trip to Hawaii.
Present –> Past
If she had enough money, she could have done this trip to Hawaii.

11. If I were you, I would be spending my vacation in Seattle.
Present –> Future
If I were you, I would be spending my vacation in Seattle.

12. Future –> Past
If I weren’t flying to Detroit, I would have planned a trip to Vancouver.

13. If I were taking this exam next week, I would be high-strung.
Future –> Present
If I were taking this exam next week,
I would be high-strung.

14. PRACTICE http://www.englishpage.com/conditional/conditional10.htm
If or Unless:
Mixed Conditionals:

15. Instead of IF RESULT CONDITION Provided/provoding that
Provided no one was looking, I’d take as much paper as I needed.
As long as
I’d tell a security guard as long as he/she agreed not to call the police
Even if (=it doesn’t matter whether the situation in the if clause exists or not)
I’d take the books, even if I had to pay a fine
Imagine/Suppose
(=form a picture in your mind about what something could be like)
Imagine/Suppose you found some library books that were due back eight months ago, would you return them?
Assuming(=accepting that something is true)
Assuming no one else saw the boy,
I’d just tell him to return the things he’d stolen