A conditional consists of two clauses: first, is the condition or the if-clause and the main or result clause.
Mixed conditional combine elements from different types (e.g., a past condition with a present result). It is also where the tense in the main clause is different from the tense in the conditional-clause (also called if-clause).
Usage:
1. Past to Present
If I had taken an aspirin, I wouldn’t have a headache now.
2. Past to Future
If I had known that you are going to come by tomorrow, I would be in then.
3. Present to Past
If she had enough money, she could have done this trip to Hawaii.
4. Present to Future
If I were you, I would be spending my vacation in Seattle.
5. Future to Past
If I weren’t flying to Detroit, I would have planned a trip to Vancouver.
6. Future to Present
If I were taking this exam next week, I would be high-strung.