I won't organise the party unless you arrange the food (if)
If you don't arrange the food, I won't organise the party
If you do the washing up, I'll make the coffee (provided)
She has a terrible headache!
She wishes she didn't have a terrible headache
Jim missed the plane and his opportunity to do business (If only)
If only Jim hadn't missed the plane and his opportunity to do business
I've been so happy since I met you (if)
If I hadn't met you , I wouldn' be so happy
I can't stand her singing so loud!!
I wish she wouldn't sing so loud!!
I think it would be a good idea to speak to the manager first ( I would...)
I would speak to the manager first if I were you