Wish clauses

WISH CLAUSES

Wish y if only pueden usarse de la misma forma. If only con frecuencia se usa para dar más énfasis al deseo o lamento.

FORMA	USO	EJEMPLOS
Wish + would / Could + Verb	Normalmente hace referencia al futuro. Queja sobre el presente o deseo de cambio.	- I wish he could be here tomorrow. - I wish she wouldn’t drive so fast. - I wish it would stop raining.
Wish + past simple	Lamento sobre una situación presente.	- I wish I knew her phone number. (I’m sorry I don’t know her number) - I wish Peter were / was here now. (Both forms are possible)
Wish + past perfect	Lamento sobre una situación pasada.	-I wish I hadn’t spent all my money. (I’m sorry I spent all my money) - If only I hadn’t eaten so much cake. (I really feel ill because I ate too much cake.)

And some exercises:

http://www.englisch-hilfen.de/en/exercises_list/if.htm

https://www.ego4u.com/en/cram-up/grammar/conditional-sentences

http://speakspeak.com/english-grammar-exercises/upper-intermediate/zero-first-second-third-conditionals